{"id":"CVE-2026-49265","aliases":["AZL-108045","DEBIAN-CVE-2026-49265","EUVD-2026-98833","GHSA-xpv3-w29h-x7cv","PYSEC-2026-4114","SUSE-SU-2026:24139-1","SUSE-SU-2026:24189-1","SUSE-SU-2026:24246-1","SUSE-SU-2026:4810-1","UBUNTU-CVE-2026-49265","openSUSE-SU-2026:22103-1"],"status":"published","title":"OAuthLib: Timing Attack Vulnerability in PKCE code_verifier Comparison","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","severity":{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00242,"percentile":0.1547,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-208"],"published":"2026-09-29T17:56:31Z","modified":"2026-11-07T14:17:41Z","fixes":[{"ecosystem":"PyPI","package":"oauthlib","fixed_in":["4.0.0"],"sources":["ghsa","osv"]},{"ecosystem":"Azure Linux:3","package":"python-oauthlib","fixed_in":["3.2.2-4"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"fixed":"4.0.0"}]}]},{"source":"osv","ecosystem":"Azure Linux:3","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-4"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.2.2-1","3.2.2-2","3.2.2-3","3.2.2-4","3.3.1-1","3.3.1-2"]},{"source":"osv","ecosystem":"Debian:13","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.2.2-3","3.2.2-4","3.3.1-1","3.3.1-2"]},{"source":"osv","ecosystem":"Debian:14","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.2.2-3","3.2.2-4","3.3.1-1","3.3.1-2"]},{"source":"osv","ecosystem":"PyPI","package":"oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"fixed":"4.0.0"}]}],"versions":["3.0.0","3.0.1","3.0.2","3.1.0","3.1.1","3.2.0","3.2.1","3.2.2","3.3.0","3.3.1"]},{"source":"osv","ecosystem":"PyPI","package":"oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"fixed":"4.0.0"}]}],"versions":["3.0.0","3.0.1","3.0.2","3.1.0","3.1.1","3.2.0","3.2.1","3.2.2","3.3.0","3.3.1"]},{"source":"osv","ecosystem":"SUSE:Linux Micro 6.0","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-159998.1.1"}]}],"bundled":2},{"source":"osv","ecosystem":"SUSE:Linux Micro 6.2","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-160000.3.1"}]}],"bundled":2},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 16.0","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-160000.3.1"}]}],"bundled":2},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP applications 16.0","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-160000.3.1"}]}],"bundled":2},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Public Cloud 15 SP4","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-150400.12.10.1"}]}],"bundled":2},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Python 3 15 SP7","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-150400.12.10.1"}]}],"bundled":2},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0-1","1.0.3-1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.1-1","2.0.4-1","2.0.6-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.0-1","3.1.0-1ubuntu1","3.1.0-1ubuntu2"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.0-2","3.1.1-1","3.2.0-1","3.2.0-1ubuntu0.1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.2.2-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.3.1-1build1","3.3.1-2"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.2.2-3","3.3.1-1","3.3.1-1build1"]},{"source":"osv","ecosystem":"openSUSE:Leap 16.0","package":"python-oauthlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.2-160000.3.1"}]}],"bundled":2}],"products":[{"vendor":"oauthlib","product":"oauthlib"}],"references":[{"url":"https://github.com/oauthlib/oauthlib/security/advisories/GHSA-xpv3-w29h-x7cv","tags":["x_refsource_CONFIRM","advisory","web","report"]},{"url":"https://github.com/oauthlib/oauthlib/pull/963","tags":["x_refsource_MISC","fix","web","report"]},{"url":"https://github.com/oauthlib/oauthlib/commit/74664d3fe037a354e180e305135c6bab1747a6b0","tags":["x_refsource_MISC","fix","report"]},{"url":"https://github.com/oauthlib/oauthlib/releases/tag/v4.0.0","tags":["x_refsource_MISC","web","report"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/oauthlib/PYSEC-2026-4114.yaml","tags":["x_refsource_MISC","advisory","web","report"]},{"url":"https://github.com/oauthlib/oauthlib/commit/40b0ab56da3682c2484a4b78bbff309f8025d950","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49265","tags":["web","advisory"]},{"url":"https://github.com/advisories/GHSA-xpv3-w29h-x7cv","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49265.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-49265","tags":["advisory"]},{"url":"https://github.com/oauthlib/oauthlib","tags":["package"]},{"url":"https://pypi.org/project/oauthlib","tags":["package"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202624139-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1283526","tags":["report"]},{"url":"https://bugzilla.suse.com/1283527","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2026-49264","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-49265","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202624189-1/","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202624246-1/","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-20264810-1/","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-49265","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-49265","tags":["report"]},{"url":"","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-49265","title":"OAuthLib: Timing Attack Vulnerability in PKCE code_verifier Comparison","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","status":"published","published":"2026-10-13T15:47:11.854Z","modified":"2026-10-13T16:19:39.092Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T13:34:59.78118Z"}],"euvd":[{"id":"EUVD-2026-98833","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","status":"published","published":"2026-10-13T15:47:11Z","modified":"2026-10-13T16:19:39Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T17:27:20.028612Z"}],"ghsa":[{"id":"GHSA-xpv3-w29h-x7cv","title":"Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (CWE-208)","description":"## Summary\n\nA timing side-channel vulnerability exists in the PKCE (RFC 7636) implementation \nof the Authorization Code Grant flow. The `code_challenge_method_plain` function \nuses Python's standard `==` operator for string comparison instead of a \nconstant-time comparison function, potentially allowing timing-based attacks.\n\n## Affected Component\n\n- File: `oauthlib/oauth2/rfc6749/grant_types/authorization_code.py`\n- Functions: `code_challenge_method_plain`, `code_challenge_method_s256`\n- Vulnerability Type: CWE-208 (Observable Timing Discrepancy)\n\n## Technical Details\n\nPython's `==` operator uses short-circuit evaluation when comparing strings:\n1. Returns `False` immediately if lengths differ\n2. Compares characters left-to-right, stopping at first mismatch\n\nThis means comparison time varies linearly with the length of the common prefix \nbetween the attacker-supplied verifier and the stored challenge, creating a \nmeasurable timing oracle.\n\n## Proof of Concept\n\nTested locally against oauthlib source (network jitter eliminated to isolate \npure Python execution time):\n\n| Input | Result | Time (10M iterations) |\n|---|---|---|\n| Wrong first char (`B` + `A`*49) | Fast reject | 0.34106s |\n| 49 chars correct (`A`*49 + `B`) | Deep compare | 0.37847s |\n| **Difference** | | **0.03741s** |\n\nThe ~37ms delta over 10M iterations corresponds to nanosecond-level differences \nper call, which are statistically exploitable under controlled conditions.\n\n## Attack Scenario\n\n1. Attacker intercepts `authorization_code` via Custom URI Scheme Hijacking\n2. PKCE blocks token request — attacker lacks `code_verifier`\n3. Attacker sends repeated requests to `/token` endpoint measuring response times\n4. Using timing oracle, attacker recovers `code_verifier` character by character\n5. Attacker obtains Access Token → Account Takeover\n\n\u003e **Note:** Practical exploitability is limited due to the single-use nature of \n\u003e authorization codes and real-world network noise. However, the vulnerable \n\u003e pattern should be corrected as a defense-in-depth measure.\n\n## Recommended Fix\n\nReplace `==` with `hmac.compare_digest()` for constant-time comparison:\n\ncr: Elvin Latifli","status":"published","published":"2026-09-29T17:56:31Z","modified":"2026-10-13T15:47:41Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T14:41:31.175024Z"}],"nvd":[{"id":"CVE-2026-49265","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","status":"published","published":"2026-10-13T16:17:20.713Z","modified":"2026-10-16T20:04:29.76Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T14:12:57.132005Z"}],"osv":[{"id":"CVE-2026-49265","title":"OAuthLib: Timing Attack Vulnerability in PKCE code_verifier Comparison","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","status":"published","published":"2026-10-13T15:47:11.854Z","modified":"2026-10-28T02:30:27.85130524Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T15:45:07.060148Z"},{"id":"DEBIAN-CVE-2026-49265","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","status":"published","published":"2026-10-13T16:17:20.713Z","modified":"2026-10-23T17:47:46.323586403Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:56.444225Z"},{"id":"GHSA-xpv3-w29h-x7cv","title":"Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (CWE-208)","description":"## Summary\n\nA timing side-channel vulnerability exists in the PKCE (RFC 7636) implementation \nof the Authorization Code Grant flow. The `code_challenge_method_plain` function \nuses Python's standard `==` operator for string comparison instead of a \nconstant-time comparison function, potentially allowing timing-based attacks.\n\n## Affected Component\n\n- File: `oauthlib/oauth2/rfc6749/grant_types/authorization_code.py`\n- Functions: `code_challenge_method_plain`, `code_challenge_method_s256`\n- Vulnerability Type: CWE-208 (Observable Timing Discrepancy)\n\n## Technical Details\n\nPython's `==` operator uses short-circuit evaluation when comparing strings:\n1. Returns `False` immediately if lengths differ\n2. Compares characters left-to-right, stopping at first mismatch\n\nThis means comparison time varies linearly with the length of the common prefix \nbetween the attacker-supplied verifier and the stored challenge, creating a \nmeasurable timing oracle.\n\n## Proof of Concept\n\nTested locally against oauthlib source (network jitter eliminated to isolate \npure Python execution time):\n\n| Input | Result | Time (10M iterations) |\n|---|---|---|\n| Wrong first char (`B` + `A`*49) | Fast reject | 0.34106s |\n| 49 chars correct (`A`*49 + `B`) | Deep compare | 0.37847s |\n| **Difference** | | **0.03741s** |\n\nThe ~37ms delta over 10M iterations corresponds to nanosecond-level differences \nper call, which are statistically exploitable under controlled conditions.\n\n## Attack Scenario\n\n1. Attacker intercepts `authorization_code` via Custom URI Scheme Hijacking\n2. PKCE blocks token request — attacker lacks `code_verifier`\n3. Attacker sends repeated requests to `/token` endpoint measuring response times\n4. Using timing oracle, attacker recovers `code_verifier` character by character\n5. Attacker obtains Access Token → Account Takeover\n\n\u003e **Note:** Practical exploitability is limited due to the single-use nature of \n\u003e authorization codes and real-world network noise. However, the vulnerable \n\u003e pattern should be corrected as a defense-in-depth measure.\n\n## Recommended Fix\n\nReplace `==` with `hmac.compare_digest()` for constant-time comparison:\n\ncr: Elvin Latifli","status":"published","published":"2026-09-29T17:56:31Z","modified":"2026-10-13T16:00:32.097492414Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium"}],"cwes":["CWE-208"],"updated_at":"2026-11-02T15:47:00.198893Z"},{"id":"PYSEC-2026-4114","title":"Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (CWE-208)","description":"## Summary\n\nA timing side-channel vulnerability exists in the PKCE (RFC 7636) implementation \nof the Authorization Code Grant flow. The `code_challenge_method_plain` function \nuses Python's standard `==` operator for string comparison instead of a \nconstant-time comparison function, potentially allowing timing-based attacks.\n\n## Affected Component\n\n- File: `oauthlib/oauth2/rfc6749/grant_types/authorization_code.py`\n- Functions: `code_challenge_method_plain`, `code_challenge_method_s256`\n- Vulnerability Type: CWE-208 (Observable Timing Discrepancy)\n\n## Technical Details\n\nPython's `==` operator uses short-circuit evaluation when comparing strings:\n1. Returns `False` immediately if lengths differ\n2. Compares characters left-to-right, stopping at first mismatch\n\nThis means comparison time varies linearly with the length of the common prefix \nbetween the attacker-supplied verifier and the stored challenge, creating a \nmeasurable timing oracle.\n\n## Proof of Concept\n\nTested locally against oauthlib source (network jitter eliminated to isolate \npure Python execution time):\n\n| Input | Result | Time (10M iterations) |\n|---|---|---|\n| Wrong first char (`B` + `A`*49) | Fast reject | 0.34106s |\n| 49 chars correct (`A`*49 + `B`) | Deep compare | 0.37847s |\n| **Difference** | | **0.03741s** |\n\nThe ~37ms delta over 10M iterations corresponds to nanosecond-level differences \nper call, which are statistically exploitable under controlled conditions.\n\n## Attack Scenario\n\n1. Attacker intercepts `authorization_code` via Custom URI Scheme Hijacking\n2. PKCE blocks token request — attacker lacks `code_verifier`\n3. Attacker sends repeated requests to `/token` endpoint measuring response times\n4. Using timing oracle, attacker recovers `code_verifier` character by character\n5. Attacker obtains Access Token → Account Takeover\n\n\u003e **Note:** Practical exploitability is limited due to the single-use nature of \n\u003e authorization codes and real-world network noise. However, the vulnerable \n\u003e pattern should be corrected as a defense-in-depth measure.\n\n## Recommended Fix\n\nReplace `==` with `hmac.compare_digest()` for constant-time comparison:\n\ncr: Elvin Latifli","status":"published","published":"2026-10-01T16:38:40.02756Z","modified":"2026-10-01T17:45:10.985894602Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T15:52:57.255153Z"},{"id":"UBUNTU-CVE-2026-49265","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","status":"published","published":"2026-10-13T16:17:00Z","modified":"2026-10-17T12:58:33.13798006Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N","level":"medium"}],"updated_at":"2026-11-02T16:56:33.391918Z"},{"id":"AZL-108045","title":"CVE-2026-49265 affecting package python-oauthlib for versions less than 3.2.2-4","description":"OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.","status":"published","published":"2026-10-13T16:17:20Z","modified":"2026-11-07T14:17:41.15680792Z","updated_at":"2026-11-07T14:48:11.583685Z"},{"id":"openSUSE-SU-2026:22103-1","title":"Security update for python-oauthlib","description":"This update for python-oauthlib fixes the following issues:\n\n- CVE-2026-49264: Oauthlib : Unsafe JSONP callback injection in RevocationEndpoint allows arbitrary JavaScript response\n  generation (bsc#1283526).\n- CVE-2026-49265: Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (bsc#1283527).\n","status":"published","published":"2026-10-14T16:09:45Z","modified":"2026-10-19T17:23:14.436927906Z","updated_at":"2026-11-02T16:58:42.426393Z"},{"id":"SUSE-SU-2026:24139-1","title":"Security update for python-oauthlib","description":"This update for python-oauthlib fixes the following issues:\n\n- CVE-2026-49264: Oauthlib : Unsafe JSONP callback injection in RevocationEndpoint allows arbitrary JavaScript response\n  generation (bsc#1283526).\n- CVE-2026-49265: Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (bsc#1283527).\n","status":"published","published":"2026-10-12T08:06:32Z","modified":"2026-10-15T17:23:12.037463013Z","updated_at":"2026-11-02T15:54:04.519245Z"},{"id":"SUSE-SU-2026:24189-1","title":"Security update for python-oauthlib","description":"This update for python-oauthlib fixes the following issues:\n\n- CVE-2026-49264: Oauthlib : Unsafe JSONP callback injection in RevocationEndpoint allows arbitrary JavaScript response\n  generation (bsc#1283526).\n- CVE-2026-49265: Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (bsc#1283527).\n","status":"published","published":"2026-10-14T16:08:36Z","modified":"2026-10-20T17:23:59.237249335Z","updated_at":"2026-11-02T15:54:04.519245Z"},{"id":"SUSE-SU-2026:24246-1","title":"Security update for python-oauthlib","description":"This update for python-oauthlib fixes the following issues:\n\n- CVE-2026-49264: Oauthlib : Unsafe JSONP callback injection in RevocationEndpoint allows arbitrary JavaScript response\n  generation (bsc#1283526).\n- CVE-2026-49265: Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (bsc#1283527).\n","status":"published","published":"2026-10-14T16:08:36Z","modified":"2026-10-21T17:23:12.343634269Z","updated_at":"2026-11-02T15:54:04.519245Z"},{"id":"SUSE-SU-2026:4810-1","title":"Security update for python-oauthlib","description":"This update for python-oauthlib fixes the following issues:\n\n- CVE-2026-49264: Oauthlib : Unsafe JSONP callback injection in RevocationEndpoint allows arbitrary JavaScript response\n  generation (bsc#1283526).\n- CVE-2026-49265: Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (bsc#1283527).\n","status":"published","published":"2026-10-21T08:05:07Z","modified":"2026-10-21T20:02:16.07049683Z","updated_at":"2026-11-02T15:54:05.838224Z"}]}}