CVE-2026-49265
Published:September 29, 2026
Updated:October 01, 2026
A timing side-channel vulnerability exists in the PKCE (RFC 7636) implementation of the Authorization Code Grant flow. The "code_challenge_method_plain" function uses Python's standard "==" operator for string comparison instead of a constant-time comparison function, potentially allowing timing-based attacks.
Affected Packages
oauthlib (CONDA):
Affected version(s) >=3.0.0 <4.0.0Fix Suggestion:
Update to version 4.0.0https://github.com/oauthlib/oauthlib.git (GITHUB):
Affected version(s) >=v3.0.0 <v4.0.0Fix Suggestion:
Update to version v4.0.0oauthlib (PYTHON):
Affected version(s) >=3.0.0 <4.0.0Fix Suggestion:
Update to version 4.0.0Related Resources (7)
Do you need more information?
Contact UsCVSS v4
Base Score:
7.6
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.8
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Observable Timing Discrepancy