Ory Oathkeeper has an authentication bypass by usage of untrusted header

MITRE NVD CVE.ORG Print: PDF PDF

Summary

CVECVE-2026-33495
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-26 18:16:30 UTC
Updated2026-03-30 13:26:50 UTC
DescriptionORY Oathkeeper is an Identity & Access Proxy (IAP) and Access Control Decision API that authorizes HTTP requests based on sets of Access Rules. Ory Oathkeeper is often deployed behind other components like CDNs, WAFs, or reverse proxies. Depending on the setup, another component might forward the request to the Oathkeeper proxy with a different protocol (http vs. https) than the original request. In order to properly match the request against the configured rules, Oathkeeper considers the `X-Forwarded-Proto` header when evaluating rules. The configuration option `serve.proxy.trust_forwarded_headers` (defaults to false) governs whether this and other `X-Forwarded-*` headers should be trusted. Prior to version 26.2.0, Oathkeeper did not properly respect this configuration, and would always consider the `X-Forwarded-Proto` header. In order for an attacker to abuse this, an installation of Ory Oathkeeper needs to have distinct rules for HTTP and HTTPS requests. Also, the attacker needs to be able to trigger one but not the other rule. In this scenario, the attacker can send the same request but with the `X-Forwarded-Proto` header in order to trigger the other rule. We do not expect many configurations to meet these preconditions. Version 26.2.0 contains a patch. Ory Oathkeeper will correctly respect the `serve.proxy.trust_forwarded_headers` configuration going forward, thereby eliminating the attack scenario. We recommend upgrading to a fixed version even if the preconditions are not met. As an additional mitigation, it is generally recommended to drop any unexpected headers as early as possible when a request is handled, e.g. in the WAF.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS: 0.000350000 probability, percentile 0.101770000 (date 2026-04-01)

Problem Types: CWE-862 | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Ory Oathkeeper affected < 26.2.0 Not specified

References

ReferenceSourceLinkTags
github.com/ory/oathkeeper/security/advisories/GHSA-vhr5-ggp3-qq85 [email protected] github.com
github.com/ory/oathkeeper/commit/e9acca14a04d246250557550065e4b4576525bd5 [email protected] github.com
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