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Ory Oathkeeper has an authentication bypass by cache key confusion

High severity GitHub Reviewed Published Mar 20, 2026 in ory/oathkeeper • Updated Mar 20, 2026

Package

gomod github.com/ory/oathkeeper (Go)

Affected versions

< 0.40.10-0.20260320084801-198a2bc82a99

Patched versions

0.40.10-0.20260320084801-198a2bc82a99

Description

Description

Ory Oathkeeper is 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.

Preconditions

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.

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 oauth2_introspection authenticators.

References

@zepatrik zepatrik published to ory/oathkeeper Mar 20, 2026
Published to the GitHub Advisory Database Mar 20, 2026
Reviewed Mar 20, 2026
Last updated Mar 20, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS score

Weaknesses

Authentication Bypass by Primary Weakness

The 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. Learn more on MITRE.

Improper Validation of Unsafe Equivalence in Input

The 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. Learn more on MITRE.

CVE ID

CVE-2026-33496

GHSA ID

GHSA-4mq7-pvjg-xp2r

Source code

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