OAuthLib: Timing Attack Vulnerability in PKCE code_verifier Comparison
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| oauthlib | oauthlib | affected |
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| Oauthlib | Oauthlib |
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| Source | ID | Title |
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Github GHSA |
GHSA-xpv3-w29h-x7cv | Oauthlib: Timing Attack Vulnerability in PKCE code_verifier Comparison (CWE-208) |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.242% probability within 30 days)
| Type | Values Removed | Values Added |
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| First Time appeared |
Oauthlib
Oauthlib oauthlib |
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| Vendors & Products |
Oauthlib
Oauthlib oauthlib |
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| Metrics |
ssvc
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| Type | Values Removed | Values Added |
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| 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. | |
| Title | OAuthLib: Timing Attack Vulnerability in PKCE code_verifier Comparison | |
| Weaknesses | CWE-208 | |
| References |
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| Metrics |
cvssV3_1
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