CVE-2026-33496: Ory Oathkeeper has an authentication bypass by cache key confusion
Description
Ory Oathkeeper is vulnerable to authentication bypass due to cache key confusion. The oauth2introspection 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.
Preconditions
Ory Oathkeeper has to be configured with multiple oauth2introspection 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.
Mitigation
Ory Oathkeeper now 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 oauth2introspection authenticators.
Other sources
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 oauth2introspection 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 oauth2introspection 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 oauth2introspection authenticators.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33496?
CVE-2026-33496 has been classified with a critical severity level due to the potential for authentication bypass.
How do I fix CVE-2026-33496?
To fix CVE-2026-33496, upgrade Ory Oathkeeper to version 0.40.10-0.20260320084801-198a2bc82a99 or a later version.
What systems are affected by CVE-2026-33496?
CVE-2026-33496 affects Ory Oathkeeper versions prior to 0.40.10-0.20260320084801-198a2bc82a99.
What impact does CVE-2026-33496 have on security?
CVE-2026-33496 allows attackers to bypass authentication, potentially gaining unauthorized access to resources.
How does CVE-2026-33496 exploit cache key confusion?
CVE-2026-33496 exploits cache key confusion by using valid tokens across different introspection URLs, allowing attackers to prime the cache.