{"id":"AZL-108045","summary":"CVE-2026-49265 affecting package python-oauthlib 3.2.2-3","details":"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.","modified":"2026-10-15T05:37:09Z","published":"2026-10-13T16:17:20Z","upstream":["CVE-2026-49265"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49265"}],"affected":[{"package":{"name":"python-oauthlib","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/python-oauthlib"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"3.2.2-3"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-108045.json"}}],"schema_version":"1.9.0"}