CVE-2026-33496: Github.com/ory/oathkeeper Authentication Bypass Vulnerability

HIGH
Advisory Identifier: GHSA-4mq7-pvjg-xp2r
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CVSS 8.1
CWE-1289 CWE-305
Published
Advisory Summary

CVE-2026-33496 is a HIGH (CVSS 8.1) authentication bypass vulnerability (CWE-1289: Improper Validation of Unsafe Equivalence in Input) affecting Github.com/ory/oathkeeper libraries in the Go ecosystem. The issue involves ory oathkeeper has an authentication bypass by cache key confusion. Remediation is available by upgrading affected packages to version 0.40.10-0.20260320084801-198a2bc82a99.

CVE-2026-33496 at a Glance

CVE Identifier CVE-2026-33496
GHSA Identifier GHSA-4mq7-pvjg-xp2r
Severity HIGH
CVSS v3.1 Base Score 8.1
CWE Classification CWE-1289: Improper Validation of Unsafe Equivalence in Input
Affected Product Github.com/ory/oathkeeper
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 8.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-33496

To remediate this vulnerability, upgrade all affected Github.com/ory/oathkeeper dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/ory/oathkeeper fixed: 0.40.10-0.20260320084801-198a2bc82a99 
Upgrade github.com/ory/oathkeeper to 0.40.10-0.20260320084801-198a2bc82a99
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/ory/oathkeeper

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-33496, inspect your project dependencies for Github.com/ory/oathkeeper:

inspect dependencies for github.com/ory/oathkeeper

Analyze the terminal output to locate any version of Github.com/ory/oathkeeper in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.40.10-0.20260320084801-198a2bc82a99), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1289: Improper Validation of Unsafe Equivalence in Input, where 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. In Github.com/ory/oathkeeper, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## 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](https://www.ory.com/docs/oathkeeper/pipeline/authn#oauth2_introspection-configuration). 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.

CVE-2026-33496 Affected Github.com/ory/oathkeeper Versions

1 component(s)
Fixed Versions:
0.40.10-0.20260320084801-198a2bc82a99
Product / Package Ecosystem Affected Versions Fixed Version
github.com/ory/oathkeeper
golang/github.com/ory/oathkeeper
Go
< 0.40.10-0.20260320084801-198a2bc82a99
0.40.10-0.20260320084801-198a2bc82a99

References

GitHub Advisory / Wiki ADVISORY
https://github.com/ory/oathkeeper/security/advisories/GHSA-4mq7-pvjg-xp2r
NVD — CVE-2026-33496 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33496
Security Fix Commit FIX COMMIT
https://github.com/ory/oathkeeper/commit/198a2bc82a99e0a77bd0ffe290cbdd5285a1b17c
Github.com/ory/oathkeeper Source Repository REPOSITORY
https://github.com/ory/oathkeeper

Frequently Asked Questions

What is CVE-2026-33496?
CVE-2026-33496 is a security vulnerability in Github.com/ory/oathkeeper involving Ory Oathkeeper has an authentication bypass by cache key confusion under CWE-1289: Improper Validation of Unsafe Equivalence in Input.
Which Github.com/ory/oathkeeper versions are affected?
Affected versions include releases prior to 0.40.10-0.20260320084801-198a2bc82a99 across affected packages: github.com/ory/oathkeeper.
What version fixes CVE-2026-33496?
Upgrading to 0.40.10-0.20260320084801-198a2bc82a99 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/ory/oathkeeper affected?
Yes, github.com/ory/oathkeeper is affected in releases prior to 0.40.10-0.20260320084801-198a2bc82a99. Upgrade your dependency to 0.40.10-0.20260320084801-198a2bc82a99 or later.
What is the CVSS score of CVE-2026-33496?
CVE-2026-33496 has a CVSS v3.1 base score of 8.1 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-33496?
CVE-2026-33496 is classified under CWE-1289: 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.).
How can I check Go dependencies for CVE-2026-33496?
Run the dependency tree command: 'inspect dependencies for github.com/ory/oathkeeper'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4mq7-pvjg-xp2r",
  "modified" : "2026-03-27T20:59:10Z",
  "published" : "2026-03-20T20:51:07Z",
  "aliases" : [ "CVE-2026-33496" ],
  "summary" : "Ory Oathkeeper has an authentication bypass by cache key confusion",
  "details" : "## Description\n\nOry 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.\n\n## Preconditions\n\nOry Oathkeeper has to be configured with multiple `oauth2_introspection` authenticator servers, each accepting different tokens. The authenticators also must be [configured to use caching](https://www.ory.com/docs/oathkeeper/pipeline/authn#oauth2_introspection-configuration). An attacker has to have a way to gain a valid token for one of the configured introspection servers.\n\n## Mitigation\n\nOry Oathkeeper now includes the introspection server URL in the cache key, preventing confusion of tokens.\n\nUpdate to the patched version of Ory Oathkeeper. If that is not immediately possible, disable caching for `oauth2_introspection` authenticators.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/ory/oathkeeper"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.40.10-0.20260320084801-198a2bc82a99"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ory/oathkeeper/security/advisories/GHSA-4mq7-pvjg-xp2r"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33496"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ory/oathkeeper/commit/198a2bc82a99e0a77bd0ffe290cbdd5285a1b17c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ory/oathkeeper"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1289", "CWE-305" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-20T20:51:07Z",
    "nvd_published_at" : "2026-03-26T18:16:30Z"
  }
}