CVE-2026-35051
Description
A flaw was found in Traefik, an HTTP reverse proxy and load balancer. This authentication bypass vulnerability exists in Traefik's ForwardAuth middleware when the trustForwardHeader setting is configured as false and Traefik is deployed behind a trusted upstream proxy. A remote attacker could exploit this to bypass authentication, potentially gaining unauthorized access to protected resources.
Mitigation
To mitigate this issue, ensure that the `trustForwardHeader` setting in Traefik's ForwardAuth middleware is not explicitly configured as `false` unless absolutely necessary. If Traefik is deployed behind a trusted upstream proxy, review the configuration to ensure that `trustForwardHeader` is either set to `true` or omitted, allowing Traefik to correctly process forwarded headers for authentication. If this configuration is modified, a restart or reload of the Traefik service may be required for the changes to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.2 | 10 | 8.2 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Changed | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | Low | High | Low |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
