The vulnerability stemmed from missing expiration checks in PKI token validation logic. The bug report (Launchpad #1179615) explicitly references auth_token.py line 1047, and patches show expiration checks were added to the token validation flow. The AuthProtocol._get_token_info function in auth_token.py was identified as the primary location where PKI tokens were processed without proper expiry validation, as confirmed by the submitted patches and discussion in the bug tracker.