CVE-2026-33496
Ory Oathkeeper has an authentication bypass by cache key confusion
In short
Ory Oathkeeper authentication proxy has a flaw where its token cache doesn't properly distinguish between tokens validated by different authentication servers, allowing an attacker with a valid token for one server to reuse it against other servers.
Technical detail
The oauth2_introspection authenticator in Ory Oathkeeper versions prior to 26.2.0 fails to include the introspection endpoint URL in the cache key, enabling cache key confusion attacks. An attacker who obtains a legitimate token for one configured OAuth2 introspection server can exploit this to bypass authentication for rules tied to a different introspection server, provided caching is enabled and multiple introspection authenticators are configured.
Summary generated and translated by AI from the official 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.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N