{"id":"CVE-2025-62706","aliases":["DEBIAN-CVE-2025-62706","DLA-4352-1","EUVD-2025-33799","GHSA-g7f3-828f-7h7m","PYSEC-2026-1202","ROOT-APP-PYPI-CVE-2025-62706","SUSE-SU-2025:3842-1","UBUNTU-CVE-2025-62706","USN-8065-1","openSUSE-SU-2026:12390-1"],"status":"published","title":"Authlib : JWE zip=DEF decompression bomb enables DoS","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00458,"percentile":0.40035,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400","CWE-770"],"published":"2025-10-10T22:54:03Z","modified":"2026-11-03T17:26:57Z","fixes":[{"ecosystem":"PyPI","package":"authlib","fixed_in":["1.6.5"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:12","package":"python-authlib","fixed_in":["1.2.0-1+deb12u1"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"python-authlib","fixed_in":["1.6.0-1+deb13u1"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"python-authlib","fixed_in":["1.6.5-1"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"rootio-Authlib","fixed_in":["1.6.4+root.io.1","1.6.4+root.io.2"],"sources":["osv"]},{"ecosystem":"Root:PyPI","package":"Authlib","fixed_in":["1.6.4+aikido.2"],"sources":["osv"]},{"ecosystem":"SUSE:Linux Enterprise Module for Python 3 15 SP6","package":"python-Authlib","fixed_in":["1.3.1-150600.3.9.1"],"sources":["osv"]},{"ecosystem":"SUSE:Linux Enterprise Module for Python 3 15 SP7","package":"python-Authlib","fixed_in":["1.3.1-150600.3.9.1"],"sources":["osv"]},{"ecosystem":"openSUSE:Leap 15.6","package":"python-Authlib","fixed_in":["1.3.1-150600.3.9.1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:22.04:LTS","package":"python-authlib","fixed_in":["0.15.5-1ubuntu0.1~esm1"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:24.04:LTS","package":"python-authlib","fixed_in":["1.3.0-1ubuntu0.1~esm1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.5"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.2.0-1+deb12u1"}]}],"versions":["1.2.0-1"]},{"source":"osv","ecosystem":"Debian:13","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.0-1+deb13u1"}]}],"versions":["1.6.0-1"]},{"source":"osv","ecosystem":"Debian:14","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.5-1"}]}],"versions":["1.6.0-1","1.6.1-1","1.6.3-1","1.6.4-1"]},{"source":"osv","ecosystem":"Debian:11","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.15.4-1+deb11u1"}]}],"versions":["0.15.4-1"],"bundled":4},{"source":"osv","ecosystem":"PyPI","package":"authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.5"}]}],"versions":["0.1","0.10","0.11","0.12","0.12.1","0.13","0.14","0.14.1","0.14.2","0.14.3","0.15","0.15.1","0.15.2","0.15.3","0.15.4","0.15.5","0.15.6","0.1rc0","0.2","0.2.1","0.3","0.4","0.4.1","0.5","0.5.1","0.6","0.7","0.8","0.9","1.0.0","1.0.0a1","1.0.0a2","1.0.0b1","1.0.0b2","1.0.0rc1","1.0.1","1.1.0","1.2.0","1.2.1","1.3.0","1.3.1","1.3.2","1.4.0","1.4.1","1.5.0","1.5.1","1.5.2","1.6.0","1.6.1","1.6.2","1.6.3","1.6.4"]},{"source":"osv","ecosystem":"PyPI","package":"authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.5"}]}],"versions":["0.1","0.10","0.11","0.12","0.12.1","0.13","0.14","0.14.1","0.14.2","0.14.3","0.15","0.15.1","0.15.2","0.15.3","0.15.4","0.15.5","0.15.6","0.1rc0","0.2","0.2.1","0.3","0.4","0.4.1","0.5","0.5.1","0.6","0.7","0.8","0.9","1.0.0","1.0.0a1","1.0.0a2","1.0.0b1","1.0.0b2","1.0.0rc1","1.0.1","1.1.0","1.2.0","1.2.1","1.3.0","1.3.1","1.3.2","1.4.0","1.4.1","1.5.0","1.5.1","1.5.2","1.6.0","1.6.1","1.6.2","1.6.3","1.6.4"]},{"source":"osv","ecosystem":"Root:PyPI","package":"rootio-Authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.4+root.io.1"},{"fixed":"1.6.4+root.io.2"}]}]},{"source":"osv","ecosystem":"Root:PyPI","package":"Authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.4+aikido.2"}]}]},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Python 3 15 SP6","package":"python-Authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.1-150600.3.9.1"}]}]},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Python 3 15 SP7","package":"python-Authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.1-150600.3.9.1"}]}]},{"source":"osv","ecosystem":"openSUSE:Leap 15.6","package":"python-Authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.1-150600.3.9.1"}]}]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.15.5-1ubuntu0.1~esm1"}]}],"versions":["0.15.4-1","0.15.5-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.0-1ubuntu0.1~esm1"}]}],"versions":["1.2.1-1","1.3.0-1"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.5.1-1","1.5.2-1","1.6.0-1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:26.04:LTS","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.6.0-1","1.6.5-1","1.6.6-1","1.6.7-1","1.6.7-1ubuntu0.1~esm1"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.15.5-1ubuntu0.1~esm1"}]}],"versions":["0.15.4-1","0.15.5-1"],"bundled":5},{"source":"osv","ecosystem":"Ubuntu:Pro:24.04:LTS","package":"python-authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.3.0-1ubuntu0.1~esm1"}]}],"versions":["1.2.1-1","1.3.0-1"],"bundled":5},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"python-Authlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.9.1-1.1"}]}],"bundled":10}],"products":[{"vendor":"authlib","product":"authlib"}],"references":[{"url":"https://github.com/authlib/authlib/security/advisories/GHSA-g7f3-828f-7h7m","tags":["x_refsource_CONFIRM","Exploit","Mitigation","Third Party Advisory","advisory","web","report"]},{"url":"https://github.com/authlib/authlib/commit/e0863d5129316b1790eee5f14cece32a03b8184d","tags":["x_refsource_MISC","Patch","fix","web","report"]},{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00032.html","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-62706","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-g7f3-828f-7h7m","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/62xxx/CVE-2025-62706.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2025-62706","tags":["advisory"]},{"url":"https://github.com/authlib/authlib","tags":["package"]},{"url":"https://pypi.org/project/authlib","tags":["package"]},{"url":"https://www.suse.com/support/update/announcement/2025/suse-su-20253842-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1252504","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2025-62706","tags":["web"]},{"url":"https://ubuntu.com/security/CVE-2025-62706","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-62706","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-8065-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2024-37568","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2025-59420","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2025-61920","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2025-68158","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2026-114614","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-114615","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-114616","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-114617","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-114618","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-114619","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-116672","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-41425","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-96760","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2025-62706","title":"Authlib : JWE zip=DEF decompression bomb enables DoS","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.","status":"published","published":"2025-10-22T21:31:10.997Z","modified":"2025-11-03T17:45:27.594Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T14:32:54.87586Z"}],"euvd":[{"id":"EUVD-2025-33799","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.","status":"published","published":"2025-10-22T21:31:10Z","modified":"2025-11-03T17:45:27Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T19:49:35.000596Z"}],"ghsa":[{"id":"GHSA-g7f3-828f-7h7m","title":"Authlib : JWE zip=DEF decompression bomb enables DoS","description":"### Summary\n_Authlib’s JWE `zip=DEF` path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service._\n\n### Details\n- Affected component: Authlib JOSE, JWE `zip=DEF` (DEFLATE) support.\n- In `authlib/authlib/jose/rfc7518/jwe_zips.py`, `DeflateZipAlgorithm.decompress` calls `zlib.decompress(s, -zlib.MAX_WBITS)` without a maximum output limit. This permits unbounded expansion of compressed payloads.\n- In the JWE decode flow (`authlib/authlib/jose/rfc7516/jwe.py`), when the protected header contains `\"zip\": \"DEF\"`, the library routes the decrypted ciphertext into the `decompress` method and assigns the fully decompressed bytes to the plaintext field before returning it. No streaming limit or quota is applied.\n- Because DEFLATE achieves extremely high ratios on highly repetitive input, an attacker can craft a tiny `zip=DEF` ciphertext that inflates to a very large plaintext during decrypt, spiking RSS and CPU. Repeated requests can starve the process or host.\n\nCode references (from this repository version):\n- `authlib/authlib/jose/rfc7518/jwe_zips.py` – `DeflateZipAlgorithm.decompress` uses unbounded `zlib.decompress`.\n- `authlib/authlib/jose/rfc7516/jwe.py` – JWE decode path applies `zip_.decompress(msg)` when `zip=DEF` is present in the header.\n\nContrast: The `joserfc` project guards `zip=DEF` decompression with a fixed maximum (256 KB) and raises `ExceededSizeError` if output would exceed this limit, preventing the bomb. Authlib lacks such a guard in this codebase snapshot.\n\n### PoC\nEnvironment: Python 3.10+ inside a venv; Authlib installed editable from this repository so source changes are visible. The PoC script demonstrates both a benign and a compressible-bomb payload and prints wall/CPU time, RSS, and size ratios.\n\n1) Create venv and install Authlib (editable):\nSet current directory to /authlib\nDownload [jwe_deflate_dos_demo.py](https://github.com/user-attachments/files/22519553/jwe_deflate_dos_demo.py) in /authlib\n```\npython3 -m venv .venv\n.venv/bin/pip install --upgrade pip\n.venv/bin/pip install -e .\n```\n\n2) Run the PoC (included in this repo):\n```\n.venv/bin/python /authlib/jwe_deflate_dos_demo.py --size 50 --max-rss-mb 2048\n```\n\nSample output (abridged):\n```\nLOCAL TEST ONLY – do not send to third-party systems.\nRuntime: Python 3.13.6 / Authlib 1.6.4 / zip=DEF via A256GCM\n[CASE] normal    plaintext=13B  ciphertext=117B decompressed=13B  wall_s=0.000 cpu_s=0.000 peak_rss_mb=31.0  ratio=0.1\n[CASE] malicious plaintext=50MB ciphertext=~4KB decompressed=50MB wall_s=~2.3  cpu_s=~2.2  peak_rss_mb=800+  ratio=12500+\n```\n\nThe second case shows the decompression spike: a few KB of ciphertext forces allocation and processing of ~50 MB during decrypt. Repeated requests can quickly exhaust available memory and CPU.\n\nReproduction notes:\n- Algorithm: `alg=dir`, `enc=A256GCM`, header includes `{ \"zip\": \"DEF\" }`.\n- The PoC uses a 32‑byte local symmetric key and a highly compressible payload (`\"A\" * N`).\n- Increase `--size` to stress memory; the `--max-rss-mb` flag helps avoid destabilizing the host during testing.\n\n### Impact\n- Effect: Denial of service (memory/CPU exhaustion) during JWE decrypt of `zip=DEF` tokens.\n- Who is impacted: Any service that uses Authlib to decrypt JWE tokens with `zip=DEF` and where an attacker can submit tokens that will be successfully decrypted (e.g., shared `dir` key, token reflection, or compromised/abused issuers).\n- Confidentiality/Integrity: No direct C/I impact; availability impact is high.\n\n### Severity (CVSS v3.1)\nBase vector (typical shared‑secret scenario where the attacker must produce a decryptable token):\n- `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` → 6.5 (MEDIUM)\n\n**Rationale:**\n- Network‑reachable (AV:N), low complexity (AC:L), no user interaction (UI:N), scope unchanged (S:U).\n- Attacker must hold or gain ability to mint a decryptable token for the target (PR:L) — common with `alg=dir` and shared keys across services.\n- No confidentiality or integrity loss (C:N/I:N); availability is severely impacted (A:H) due to decompression expansion.\nIf arbitrary unprivileged parties can submit JWEs that will be decrypted (PR:N), the base vector becomes:\n- `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` → 7.5 (HIGH)\n\n### Mitigations / Workarounds\n- Reject or strip `zip=DEF` for inbound JWEs at the application boundary until a fix is available.\n- Fork and add a bounded decompression guard (e.g., `zlib.decompress(..., max_length)` via `decompressobj().decompress(data, MAX_SIZE)`), returning an error when output exceeds a safe limit.\n- Enforce strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.\n\n### Remediation Guidance (for maintainers)\n- Mirror `joserfc`’s approach: add a conservative maximum output size (e.g., 256 KB by default) and raise a specific error when exceeded; document a controlled way to raise this ceiling for trusted environments.\n- Consider streaming decode with chunked limits to avoid large single allocations.\n\n### References\n- Authlib source: `authlib/authlib/jose/rfc7518/jwe_zips.py`, `authlib/authlib/jose/rfc7516/jwe.py`","status":"published","published":"2025-10-10T22:54:03Z","modified":"2025-11-03T18:31:47Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T14:39:04.350802Z"}],"nvd":[{"id":"CVE-2025-62706","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.","status":"published","published":"2025-10-22T22:15:35.557Z","modified":"2026-10-19T13:10:00.11Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T14:11:39.579859Z"}],"osv":[{"id":"CVE-2025-62706","title":"Authlib : JWE zip=DEF decompression bomb enables DoS","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.","status":"published","published":"2025-10-22T21:31:10.997Z","modified":"2026-11-03T17:26:57.302570693Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-03T18:00:18.501611Z"},{"id":"DEBIAN-CVE-2025-62706","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.","status":"published","published":"2025-10-22T22:15:35.557Z","modified":"2026-10-23T17:47:23.132135353Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:45:47.697959Z"},{"id":"GHSA-g7f3-828f-7h7m","title":"Authlib : JWE zip=DEF decompression bomb enables DoS","description":"### Summary\n_Authlib’s JWE `zip=DEF` path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service._\n\n### Details\n- Affected component: Authlib JOSE, JWE `zip=DEF` (DEFLATE) support.\n- In `authlib/authlib/jose/rfc7518/jwe_zips.py`, `DeflateZipAlgorithm.decompress` calls `zlib.decompress(s, -zlib.MAX_WBITS)` without a maximum output limit. This permits unbounded expansion of compressed payloads.\n- In the JWE decode flow (`authlib/authlib/jose/rfc7516/jwe.py`), when the protected header contains `\"zip\": \"DEF\"`, the library routes the decrypted ciphertext into the `decompress` method and assigns the fully decompressed bytes to the plaintext field before returning it. No streaming limit or quota is applied.\n- Because DEFLATE achieves extremely high ratios on highly repetitive input, an attacker can craft a tiny `zip=DEF` ciphertext that inflates to a very large plaintext during decrypt, spiking RSS and CPU. Repeated requests can starve the process or host.\n\nCode references (from this repository version):\n- `authlib/authlib/jose/rfc7518/jwe_zips.py` – `DeflateZipAlgorithm.decompress` uses unbounded `zlib.decompress`.\n- `authlib/authlib/jose/rfc7516/jwe.py` – JWE decode path applies `zip_.decompress(msg)` when `zip=DEF` is present in the header.\n\nContrast: The `joserfc` project guards `zip=DEF` decompression with a fixed maximum (256 KB) and raises `ExceededSizeError` if output would exceed this limit, preventing the bomb. Authlib lacks such a guard in this codebase snapshot.\n\n### PoC\nEnvironment: Python 3.10+ inside a venv; Authlib installed editable from this repository so source changes are visible. The PoC script demonstrates both a benign and a compressible-bomb payload and prints wall/CPU time, RSS, and size ratios.\n\n1) Create venv and install Authlib (editable):\nSet current directory to /authlib\nDownload [jwe_deflate_dos_demo.py](https://github.com/user-attachments/files/22519553/jwe_deflate_dos_demo.py) in /authlib\n```\npython3 -m venv .venv\n.venv/bin/pip install --upgrade pip\n.venv/bin/pip install -e .\n```\n\n2) Run the PoC (included in this repo):\n```\n.venv/bin/python /authlib/jwe_deflate_dos_demo.py --size 50 --max-rss-mb 2048\n```\n\nSample output (abridged):\n```\nLOCAL TEST ONLY – do not send to third-party systems.\nRuntime: Python 3.13.6 / Authlib 1.6.4 / zip=DEF via A256GCM\n[CASE] normal    plaintext=13B  ciphertext=117B decompressed=13B  wall_s=0.000 cpu_s=0.000 peak_rss_mb=31.0  ratio=0.1\n[CASE] malicious plaintext=50MB ciphertext=~4KB decompressed=50MB wall_s=~2.3  cpu_s=~2.2  peak_rss_mb=800+  ratio=12500+\n```\n\nThe second case shows the decompression spike: a few KB of ciphertext forces allocation and processing of ~50 MB during decrypt. Repeated requests can quickly exhaust available memory and CPU.\n\nReproduction notes:\n- Algorithm: `alg=dir`, `enc=A256GCM`, header includes `{ \"zip\": \"DEF\" }`.\n- The PoC uses a 32‑byte local symmetric key and a highly compressible payload (`\"A\" * N`).\n- Increase `--size` to stress memory; the `--max-rss-mb` flag helps avoid destabilizing the host during testing.\n\n### Impact\n- Effect: Denial of service (memory/CPU exhaustion) during JWE decrypt of `zip=DEF` tokens.\n- Who is impacted: Any service that uses Authlib to decrypt JWE tokens with `zip=DEF` and where an attacker can submit tokens that will be successfully decrypted (e.g., shared `dir` key, token reflection, or compromised/abused issuers).\n- Confidentiality/Integrity: No direct C/I impact; availability impact is high.\n\n### Severity (CVSS v3.1)\nBase vector (typical shared‑secret scenario where the attacker must produce a decryptable token):\n- `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` → 6.5 (MEDIUM)\n\n**Rationale:**\n- Network‑reachable (AV:N), low complexity (AC:L), no user interaction (UI:N), scope unchanged (S:U).\n- Attacker must hold or gain ability to mint a decryptable token for the target (PR:L) — common with `alg=dir` and shared keys across services.\n- No confidentiality or integrity loss (C:N/I:N); availability is severely impacted (A:H) due to decompression expansion.\nIf arbitrary unprivileged parties can submit JWEs that will be decrypted (PR:N), the base vector becomes:\n- `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` → 7.5 (HIGH)\n\n### Mitigations / Workarounds\n- Reject or strip `zip=DEF` for inbound JWEs at the application boundary until a fix is available.\n- Fork and add a bounded decompression guard (e.g., `zlib.decompress(..., max_length)` via `decompressobj().decompress(data, MAX_SIZE)`), returning an error when output exceeds a safe limit.\n- Enforce strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.\n\n### Remediation Guidance (for maintainers)\n- Mirror `joserfc`’s approach: add a conservative maximum output size (e.g., 256 KB by default) and raise a specific error when exceeded; document a controlled way to raise this ceiling for trusted environments.\n- Consider streaming decode with chunked limits to avoid large single allocations.\n\n### References\n- Authlib source: `authlib/authlib/jose/rfc7518/jwe_zips.py`, `authlib/authlib/jose/rfc7516/jwe.py`","status":"published","published":"2025-10-10T22:54:03Z","modified":"2026-09-10T03:50:29.792893044Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-400","CWE-770"],"updated_at":"2026-11-02T15:46:47.472172Z"},{"id":"PYSEC-2026-1202","title":"Authlib : JWE zip=DEF decompression bomb enables DoS","description":"### Summary\n_Authlib’s JWE `zip=DEF` path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service._\n\n### Details\n- Affected component: Authlib JOSE, JWE `zip=DEF` (DEFLATE) support.\n- In `authlib/authlib/jose/rfc7518/jwe_zips.py`, `DeflateZipAlgorithm.decompress` calls `zlib.decompress(s, -zlib.MAX_WBITS)` without a maximum output limit. This permits unbounded expansion of compressed payloads.\n- In the JWE decode flow (`authlib/authlib/jose/rfc7516/jwe.py`), when the protected header contains `\"zip\": \"DEF\"`, the library routes the decrypted ciphertext into the `decompress` method and assigns the fully decompressed bytes to the plaintext field before returning it. No streaming limit or quota is applied.\n- Because DEFLATE achieves extremely high ratios on highly repetitive input, an attacker can craft a tiny `zip=DEF` ciphertext that inflates to a very large plaintext during decrypt, spiking RSS and CPU. Repeated requests can starve the process or host.\n\nCode references (from this repository version):\n- `authlib/authlib/jose/rfc7518/jwe_zips.py` – `DeflateZipAlgorithm.decompress` uses unbounded `zlib.decompress`.\n- `authlib/authlib/jose/rfc7516/jwe.py` – JWE decode path applies `zip_.decompress(msg)` when `zip=DEF` is present in the header.\n\nContrast: The `joserfc` project guards `zip=DEF` decompression with a fixed maximum (256 KB) and raises `ExceededSizeError` if output would exceed this limit, preventing the bomb. Authlib lacks such a guard in this codebase snapshot.\n\n### PoC\nEnvironment: Python 3.10+ inside a venv; Authlib installed editable from this repository so source changes are visible. The PoC script demonstrates both a benign and a compressible-bomb payload and prints wall/CPU time, RSS, and size ratios.\n\n1) Create venv and install Authlib (editable):\nSet current directory to /authlib\nDownload [jwe_deflate_dos_demo.py](https://github.com/user-attachments/files/22519553/jwe_deflate_dos_demo.py) in /authlib\n```\npython3 -m venv .venv\n.venv/bin/pip install --upgrade pip\n.venv/bin/pip install -e .\n```\n\n2) Run the PoC (included in this repo):\n```\n.venv/bin/python /authlib/jwe_deflate_dos_demo.py --size 50 --max-rss-mb 2048\n```\n\nSample output (abridged):\n```\nLOCAL TEST ONLY – do not send to third-party systems.\nRuntime: Python 3.13.6 / Authlib 1.6.4 / zip=DEF via A256GCM\n[CASE] normal    plaintext=13B  ciphertext=117B decompressed=13B  wall_s=0.000 cpu_s=0.000 peak_rss_mb=31.0  ratio=0.1\n[CASE] malicious plaintext=50MB ciphertext=~4KB decompressed=50MB wall_s=~2.3  cpu_s=~2.2  peak_rss_mb=800+  ratio=12500+\n```\n\nThe second case shows the decompression spike: a few KB of ciphertext forces allocation and processing of ~50 MB during decrypt. Repeated requests can quickly exhaust available memory and CPU.\n\nReproduction notes:\n- Algorithm: `alg=dir`, `enc=A256GCM`, header includes `{ \"zip\": \"DEF\" }`.\n- The PoC uses a 32‑byte local symmetric key and a highly compressible payload (`\"A\" * N`).\n- Increase `--size` to stress memory; the `--max-rss-mb` flag helps avoid destabilizing the host during testing.\n\n### Impact\n- Effect: Denial of service (memory/CPU exhaustion) during JWE decrypt of `zip=DEF` tokens.\n- Who is impacted: Any service that uses Authlib to decrypt JWE tokens with `zip=DEF` and where an attacker can submit tokens that will be successfully decrypted (e.g., shared `dir` key, token reflection, or compromised/abused issuers).\n- Confidentiality/Integrity: No direct C/I impact; availability impact is high.\n\n### Severity (CVSS v3.1)\nBase vector (typical shared‑secret scenario where the attacker must produce a decryptable token):\n- `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` → 6.5 (MEDIUM)\n\n**Rationale:**\n- Network‑reachable (AV:N), low complexity (AC:L), no user interaction (UI:N), scope unchanged (S:U).\n- Attacker must hold or gain ability to mint a decryptable token for the target (PR:L) — common with `alg=dir` and shared keys across services.\n- No confidentiality or integrity loss (C:N/I:N); availability is severely impacted (A:H) due to decompression expansion.\nIf arbitrary unprivileged parties can submit JWEs that will be decrypted (PR:N), the base vector becomes:\n- `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` → 7.5 (HIGH)\n\n### Mitigations / Workarounds\n- Reject or strip `zip=DEF` for inbound JWEs at the application boundary until a fix is available.\n- Fork and add a bounded decompression guard (e.g., `zlib.decompress(..., max_length)` via `decompressobj().decompress(data, MAX_SIZE)`), returning an error when output exceeds a safe limit.\n- Enforce strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.\n\n### Remediation Guidance (for maintainers)\n- Mirror `joserfc`’s approach: add a conservative maximum output size (e.g., 256 KB by default) and raise a specific error when exceeded; document a controlled way to raise this ceiling for trusted environments.\n- Consider streaming decode with chunked limits to avoid large single allocations.\n\n### References\n- Authlib source: `authlib/authlib/jose/rfc7518/jwe_zips.py`, `authlib/authlib/jose/rfc7516/jwe.py`","status":"published","published":"2026-07-07T16:03:07.522275Z","modified":"2026-07-07T17:46:32.698664924Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:52:54.622769Z"},{"id":"ROOT-APP-PYPI-CVE-2025-62706","title":"CVE-2025-62706 in rootio-Authlib - Patched by Root","description":"Root has patched CVE-2025-62706 in the rootio-Authlib package for Root:PyPI. Multiple fixed versions available.","status":"published","published":"2026-06-03T14:51:07Z","modified":"2026-06-03T19:30:25.71337877Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T15:53:27.940619Z"},{"id":"UBUNTU-CVE-2025-62706","description":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt, allowing an attacker who can supply decryptable tokens to exhaust memory and CPU and cause denial of service. This issue has been patched in version 1.6.5. Workarounds for this issue involve rejecting or stripping zip=DEF for inbound JWEs at the application boundary, forking and add a bounded decompression guard via decompressobj().decompress(data, MAX_SIZE)) and returning an error when output exceeds a safe limit, or enforcing strict maximum token sizes and fail fast on oversized inputs; combine with rate limiting.","status":"published","published":"2025-10-22T22:15:00Z","modified":"2026-07-16T20:48:19.491951648Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T16:55:50.817402Z"},{"id":"DLA-4352-1","title":"python-authlib - security update","status":"published","published":"2025-10-29T00:00:00Z","modified":"2025-10-29T04:34:52.744951Z","updated_at":"2026-11-02T15:46:12.7027Z"},{"id":"openSUSE-SU-2026:12390-1","title":"python313-Authlib-1.9.1-1.1 on GA media","description":"These are all security issues fixed in the python313-Authlib-1.9.1-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-11-02T00:00:00Z","modified":"2026-11-03T17:23:11.947045508Z","updated_at":"2026-11-03T18:00:34.078068Z"},{"id":"SUSE-SU-2025:3842-1","title":"Security update for python-Authlib","description":"This update for python-Authlib fixes the following issues:\n\n  - CVE-2025-62706: fixed a denial of service condition  (bsc#1252504, gh#authlib/authlib@e0863d512931)\n","status":"published","published":"2025-10-28T16:39:39Z","modified":"2026-03-23T04:49:19.16278Z","updated_at":"2026-11-02T15:54:00.344164Z"},{"id":"USN-8065-1","title":"python-authlib vulnerabilities","description":"Millie Solem discovered that Authlib did not properly restrict algorithm\nselection during JWT verification, allowing HMAC verification with\nasymmetric public keys when no algorithm was specified. A remote attacker\ncould possibly use this issue to bypass signature verification and forge\ntokens, resulting in authentication bypass or privilege escalation.\n(CVE-2024-37568)\n\nMuhammad Noman Ilyas discovered that Authlib did not properly enforce\ncritical header parameter handling during JSON Web Signature verification,\nleading to unknown critical parameters being incorrectly accepted. A remote\nattacker could possibly use this issue to bypass security policies in mixed\ndeployments, resulting in authentication bypass, replay attacks, or\nprivilege escalation. (CVE-2025-59420)\n\nMuhammad Noman Ilyas discovered that Authlib did not properly limit the\nsize of JSON Web Signature or JSON Web Token header and signature segments.\nA remote attacker could possibly use this issue to cause excessive memory\nor processor consumption, leading to a denial of service. (CVE-2025-61920)\n\nMuhammad Noman Ilyas discovered that Authlib performed unbounded\ndecompression when processing certain compressed encrypted tokens. A remote\nattacker could possibly use this issue to send a specially crafted token\nthat can be expanded to a large size during decompression, causing a denial\nof service. (CVE-2025-62706)\n\nIt was discovered that Authlib did not properly bind cached state\ninformation to the initiating user session during OAuth authentication\nflows. A remote attacker could possibly use this issue to perform cross-\nsite request forgery attacks, resulting in unauthorized actions or\nauthentication bypass. This issue only affected Ubuntu 24.04 LTS.\n(CVE-2025-68158)","status":"published","published":"2026-02-25T20:43:00Z","modified":"2026-04-27T18:41:08.675153Z","updated_at":"2026-11-02T16:58:22.951676Z"}]}}