CVE-2026-85595
Description
An authentication bypass vulnerability was discovered in Traefik's digestAuth middleware. When an incoming request contains a username that does not exist in the configured authentication store, the application fails to reject the request and instead evaluates the credential against an empty string secret. An unauthenticated remote attacker can exploit this flaw by generating a valid HTTP Digest Authentication header calculated using an empty secret and an arbitrary password, successfully bypassing authentication controls and gaining unauthorized access to routes protected by the digestAuth middleware.
Statement
A flaw was found in Traefik's digestAuth middleware (versions before v2.11.55 and v3.0.0 through v3.7.10) where requests with unknown usernames are processed using an empty secret instead of being immediately rejected. Within Red Hat environments utilizing affected Traefik components, an unauthenticated remote attacker can exploit this default state by computing a valid HTTP digest response using an empty secret and arbitrary credentials, successfully bypassing authentication on any digestAuth-protected endpoint.
Mitigation
Disable the digestAuth middleware and transition to alternative authentication mechanisms such as basicAuth, ForwardAuth, or mTLS. Alternatively, restrict network access to digestAuth-protected routes at an upstream gateway or network firewall until patched.
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 | 9.1 | 9.8 | 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 | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
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