CVE-2026-33496: Ory Oathkeeper has an authentication bypass by cache key confusion

Vulnerability summary

CVE-2026-33496 is a high (CVSS 8.1) vulnerability in ory oathkeeper. EPSS estimates a 0.38% chance of exploitation in the next 30 days, higher than 32.5% of scored vulnerabilities.

Timeline

1. 26-03-2026
   PublishedVulnerability first disclosed.
2. 30-03-2026
   Last modifiedVulnerability information updated.

Description

ORY Oathkeeper is an Identity & Access Proxy (IAP) and Access Control Decision API that authorizes HTTP requests based on sets of Access Rules. Versions prior to 26.2.0 are vulnerable to authentication bypass due to cache key confusion. The `oauth2_introspection` authenticator cache does not distinguish tokens that were validated with different introspection URLs. An attacker can therefore legitimately use a token to prime the cache, and subsequently use the same token for rules that use a different introspection server. Ory Oathkeeper has to be configured with multiple `oauth2_introspection` authenticator servers, each accepting different tokens. The authenticators also must be configured to use caching. An attacker has to have a way to gain a valid token for one of the configured introspection servers. Starting in version 26.2.0, Ory Oathkeeper includes the introspection server URL in the cache key, preventing confusion of tokens. Update to the patched version of Ory Oathkeeper. If that is not immediately possible, disable caching for `oauth2_introspection` authenticators.

• CWE-305Authentication Bypass by Primary WeaknessThe authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.
• CWE-1289Improper Validation of Unsafe Equivalence in InputThe product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.