CVE-2025-55162: Envoy: oAuth2 Filter Signout route will not clear cookies because of missing "secure;" flag

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-09-03 · updated 2026-06-17
Weakness: CWE-613

Description

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In versions below 1.32.10 and 1.33.0 through 1.33.6, 1.34.0 through 1.34.4 and 1.35.0, 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 current implementation iterates through the configured cookie names to generate deletion headers but does not check for these prefixes. This failure to properly construct the deletion header means the user's session cookies are never removed by the browser, leaving the session active and allowing the next user of the same browser to gain unauthorized access to the original user's account and data. This is fixed in versions 1.32.10, 1.33.7, 1.34.5 and 1.35.1.

Affected products

envoyproxy envoy: before 1.32.10; from 1.33.0 through 1.33.7; from 1.34.0 before 1.34.5; 1.35.0 — fixed in 1.32.10, 1.34.5

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.32.10, 1.34.5. Check the vendor advisory for mitigations.

References

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