CVE-2026-54763
Description
A flaw was found in Traefik, an HTTP reverse proxy and load balancer. The BasicAuth, DigestAuth, and ForwardAuth middlewares in Traefik do not correctly treat underscore-variant header names. This allows a remote attacker to inject a specially crafted header that bypasses Traefik's security mechanisms. As a result, the attacker can spoof identity or authorization context to the backend, potentially gaining unauthorized access to protected resources.
Statement
Important: This flaw in Traefik's authentication middlewares allows a remote attacker to bypass security mechanisms by injecting specially crafted underscore-variant headers. This can lead to identity spoofing or unauthorized access to backend services, as Traefik fails to properly strip these headers before forwarding them. The vulnerability is significant because many backend systems normalize these header forms, making exploitation feasible in typical deployments.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 10 | 10 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Changed | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Frequently Asked Questions
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