Description (CNA)
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.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| oauthlib / oauthlib | affected >= 3.0.0, < 4.0.0 |
CWE
CWE-208
References
- https://github.com/oauthlib/oauthlib/security/advisories/GHSA-xpv3-w29h-x7cv
- https://github.com/oauthlib/oauthlib/pull/963
- https://github.com/oauthlib/oauthlib/commit/74664d3fe037a354e180e305135c6bab1747a6b0
- https://github.com/oauthlib/oauthlib/releases/tag/v4.0.0
- https://github.com/pypa/advisory-database/tree/main/vulns/oauthlib/PYSEC-2026-4114.yaml
ADP enrichment
No English description supplied.
No references supplied.