{"id":"CVE-2026-119284","aliases":["DEBIAN-CVE-2026-119284","EUVD-2026-113401","GHSA-9pg5-8c7x-5hfx","UBUNTU-CVE-2026-119284"],"status":"published","title":"joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.","severity":{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00192,"percentile":0.08968,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400"],"published":"2026-10-29T21:33:16Z","modified":"2026-11-05T04:42:51Z","fixes":[{"ecosystem":"PyPI","package":"joserfc","fixed_in":["1.7.6"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:14","package":"joserfc","fixed_in":["1.7.7-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"joserfc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.7.6"}]}]},{"source":"osv","ecosystem":"Debian:13","package":"joserfc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1.0-1","1.2.0-1","1.2.2-1","1.3.1-1","1.3.2-1","1.3.4-1","1.4.0-1","1.4.1-1","1.4.3-1","1.5.0-1","1.6.0-1","1.6.1-1","1.6.2-1","1.6.3-1","1.6.4-1","1.6.5-1","1.6.8-1","1.7.0-1","1.7.1-1","1.7.2-1","1.7.3-1","1.7.4-1","1.7.5-1","1.7.7-1"]},{"source":"osv","ecosystem":"Debian:14","package":"joserfc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.7.7-1"}]}],"versions":["1.1.0-1","1.2.0-1","1.2.2-1","1.3.1-1","1.3.2-1","1.3.4-1","1.4.0-1","1.4.1-1","1.4.3-1","1.5.0-1","1.6.0-1","1.6.1-1","1.6.2-1","1.6.3-1","1.6.4-1","1.6.5-1","1.6.8-1","1.7.0-1","1.7.1-1","1.7.2-1","1.7.3-1","1.7.4-1","1.7.5-1"]},{"source":"osv","ecosystem":"PyPI","package":"joserfc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.7.6"}]}],"versions":["0.1.0","0.10.0","0.11.0","0.11.1","0.12.0","0.2.0","0.3.0","0.4.0","0.5.0","0.6.0","0.7.0","0.8.0","0.9.0","1.0.0","1.0.1","1.0.2","1.0.3","1.0.4","1.1.0","1.2.0","1.2.1","1.2.2","1.3.0","1.3.1","1.3.2","1.3.3","1.3.4","1.3.5","1.4.0","1.4.1","1.4.2","1.4.3","1.5.0","1.6.0","1.6.1","1.6.2","1.6.3","1.6.4","1.6.5","1.6.7","1.6.8","1.7.0","1.7.1","1.7.2","1.7.3","1.7.4","1.7.5"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"joserfc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.6.2-1","1.6.5-1","1.6.8-1","1.7.0-1","1.7.1-1","1.7.2-1","1.7.4-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"joserfc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.2-1","1.4.0-1","1.4.1-1","1.4.3-1","1.5.0-1","1.6.2-1"]}],"products":[{"vendor":"authlib","product":"joserfc"}],"references":[{"url":"https://github.com/authlib/joserfc/security/advisories/GHSA-9pg5-8c7x-5hfx","tags":["x_refsource_CONFIRM","exploit","advisory","web","report"]},{"url":"https://github.com/authlib/joserfc/commit/397e04f4bbce0b94d86e31c1c003f4640af8fb39","tags":["x_refsource_MISC","fix","web","report"]},{"url":"https://github.com/authlib/joserfc/releases/tag/1.7.6","tags":["x_refsource_MISC","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119284","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-9pg5-8c7x-5hfx"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/119xxx/CVE-2026-119284.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-119284","tags":["advisory"]},{"url":"https://github.com/authlib/joserfc","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-119284","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-119284","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-119284","title":"joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.","status":"published","published":"2026-10-29T21:33:16.529Z","modified":"2026-10-30T17:05:38.184Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium","assessor":"cna"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:20:10.143031Z"}],"euvd":[{"id":"EUVD-2026-113401","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.","status":"published","published":"2026-10-29T21:33:16Z","modified":"2026-10-30T17:05:38Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-02T16:59:05.567782Z"}],"ghsa":[{"id":"GHSA-9pg5-8c7x-5hfx","title":"joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection","description":"## Summary\n\njoserfc 1.7.4 defines compact-JWS header, payload, and signature limits, but\ncalls `value.split(b\".\")` before validating them. Python `bytes.split()` copies\nthe attacker-controlled segments, so the current guard allocates roughly one\ncomplete payload before rejecting it.\n\n## Reproduction\n\n```bash\n.venv-research/bin/python 06-practical-testing/preauth-memory-profile.py\n```\n\nThe input is resident before a fork-isolated verifier runs, and every signature\nis invalid.\n\n| Input | Peak RSS delta | Amplification | Result |\n|---:|---:|---:|---|\n| 1 MiB | 1.11 MiB | 1.11× | size rejected |\n| 4 MiB | 4.04 MiB | 1.01× | size rejected |\n| 8 MiB | 8.04 MiB | 1.01× | size rejected |\n| 16 MiB | 16.04 MiB | 1.00× | size rejected |\n| 32 MiB | 31.74 MiB | 0.99× | size rejected |\n| 64 MiB | 63.80 MiB | 1.00× | size rejected |\n\nThe unconstrained profile is the primary evidence: joserfc allocates an\nadditional attacker-sized object before producing its intended\n`ExceededSizeError`. A separate baseline-plus-headroom stress test raises\n`MemoryError` when that copy cannot fit, but this report does not characterize\nan absolute `RLIMIT_AS` value as a realistic worker memory budget.\n\n## Security Argument\n\nThe issue is not that joserfc can prevent the transport layer from receiving a\nlarge header. The issue is narrower: once bytes reach `deserialize_compact()`,\nthe library's existing size guard cannot fulfill its allocation-limiting purpose\nbecause attacker-controlled segment copies are created first.\n\nThis differs from\n[GHSA-frfh-8v73-gjg4](https://github.com/authlib/joserfc/security/advisories/GHSA-frfh-8v73-gjg4),\nwhich concerned embedding already-loaded oversized segments in exception and log\nmessages. Here, the current implementation itself creates an additional\npayload-sized allocation before its fixed size exception.\n\n## Recommended Fix\n\nCheck `len(value)` against a maximum compact-serialization size before\n`split()`. If per-segment diagnostics are needed, locate delimiters with bounded\n`find()` operations or memory views, validate offsets and lengths, and only then\nmaterialize acceptable segments.","status":"published","published":"2026-10-30T14:54:25Z","modified":"2026-10-30T14:54:26Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:41:41.028239Z"}],"nvd":[{"id":"CVE-2026-119284","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.","status":"published","published":"2026-10-29T22:17:01.21Z","modified":"2026-10-30T17:17:17.85Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:13:04.940026Z"}],"osv":[{"id":"CVE-2026-119284","title":"joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.","status":"published","published":"2026-10-29T21:33:16.529Z","modified":"2026-11-01T02:30:55.252896227Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:44:57.008854Z"},{"id":"DEBIAN-CVE-2026-119284","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.","status":"published","published":"2026-10-29T22:17:01.21Z","modified":"2026-10-31T09:47:26.399088462Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium"}],"updated_at":"2026-11-02T15:45:51.374409Z"},{"id":"GHSA-9pg5-8c7x-5hfx","title":"joserfc: Compact JWS size guard allocates attacker-controlled segments before rejection","description":"## Summary\n\njoserfc 1.7.4 defines compact-JWS header, payload, and signature limits, but\ncalls `value.split(b\".\")` before validating them. Python `bytes.split()` copies\nthe attacker-controlled segments, so the current guard allocates roughly one\ncomplete payload before rejecting it.\n\n## Reproduction\n\n```bash\n.venv-research/bin/python 06-practical-testing/preauth-memory-profile.py\n```\n\nThe input is resident before a fork-isolated verifier runs, and every signature\nis invalid.\n\n| Input | Peak RSS delta | Amplification | Result |\n|---:|---:|---:|---|\n| 1 MiB | 1.11 MiB | 1.11× | size rejected |\n| 4 MiB | 4.04 MiB | 1.01× | size rejected |\n| 8 MiB | 8.04 MiB | 1.01× | size rejected |\n| 16 MiB | 16.04 MiB | 1.00× | size rejected |\n| 32 MiB | 31.74 MiB | 0.99× | size rejected |\n| 64 MiB | 63.80 MiB | 1.00× | size rejected |\n\nThe unconstrained profile is the primary evidence: joserfc allocates an\nadditional attacker-sized object before producing its intended\n`ExceededSizeError`. A separate baseline-plus-headroom stress test raises\n`MemoryError` when that copy cannot fit, but this report does not characterize\nan absolute `RLIMIT_AS` value as a realistic worker memory budget.\n\n## Security Argument\n\nThe issue is not that joserfc can prevent the transport layer from receiving a\nlarge header. The issue is narrower: once bytes reach `deserialize_compact()`,\nthe library's existing size guard cannot fulfill its allocation-limiting purpose\nbecause attacker-controlled segment copies are created first.\n\nThis differs from\n[GHSA-frfh-8v73-gjg4](https://github.com/authlib/joserfc/security/advisories/GHSA-frfh-8v73-gjg4),\nwhich concerned embedding already-loaded oversized segments in exception and log\nmessages. Here, the current implementation itself creates an additional\npayload-sized allocation before its fixed size exception.\n\n## Recommended Fix\n\nCheck `len(value)` against a maximum compact-serialization size before\n`split()`. If per-segment diagnostics are needed, locate delimiters with bounded\n`find()` operations or memory views, validate offsets and lengths, and only then\nmaterialize acceptable segments.","status":"published","published":"2026-10-30T14:54:25Z","modified":"2026-10-30T15:15:03.588544987Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:46:43.875515Z"},{"id":"UBUNTU-CVE-2026-119284","description":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.6, joserfc compact JWS deserialization calls bytes.split() before enforcing the existing aggregate segment-size limits. When attacker-controlled compact serialization bytes reach deserialize_compact(), the split creates copies of the header, payload, and signature segments before ExceededSizeError rejects them, causing an additional allocation approximately proportional to the supplied token. Requests that exhaust available process memory can therefore cause an availability failure even though signature verification fails. This issue is fixed in version 1.7.6.","status":"published","published":"2026-10-29T22:17:00Z","modified":"2026-11-05T04:42:51Z","cvss":[{"version":"4.0","score":6.9,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","level":"medium"}],"updated_at":"2026-11-05T13:33:25.727744Z"}]}}