Thomas Brüggemann

**Name of the Vulnerable Software and Affected Versions** Envoy versions prior to 1.32.10 Envoy versions 1.33.0 through 1.33.6 Envoy versions 1.34.0 through 1.34.4 Envoy versions 1.35.0 **Description** Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. Insufficient Session Expiration in the Envoy OAuth2 filter leads to failed logout operations. When configured with ` Secure-` or ` Host-` prefixed cookie names, the filter fails to append the required Secure attribute to the Set-Cookie header during deletion. Modern browsers ignore this invalid request, causing the session cookie to persist. This allows a user to remain logged in after they believe they have logged out, creating a session hijacking risk on shared computers. The issue arises because the implementation iterates through configured cookie names to generate deletion headers but does not check for these prefixes, resulting in improperly constructed deletion headers and persistent session cookies. **Recommendations** Update to Envoy version 1.32.10 or later. Update to Envoy version 1.33.7 or later. Update to Envoy version 1.34.5 or later. Update to Envoy version 1.35.1 or later.