CVE-2026-85595: Traefik before v2.11.55 Authentication Bypass via digestAuth
Traefik versions before v2.11.55 contain an authentication bypass vulnerability in the digestAuth middleware where unknown usernames receive an empty secret instead of rejection. Attackers can compute a valid digest response using the empty secret and arbitrary credentials to bypass authentication on any digestAuth-protected route without a valid username or password.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Traefik digestAuth middlewareto a version that resolves this vulnerability.Fixed in 2.11.55
Event History
Frequently Asked Questions
Which deployments are exposed?
Any Traefik deployment running a version before 2.11.55 is exposed if it uses the digestAuth middleware to protect one or more routes. Routes protected by other mechanisms are not identified as affected by the provided information.
What does an attacker need to bypass authentication?
The attacker does not need a valid username or password. They can use an unknown username and compute a valid digest response using the empty secret assigned to unknown users.
How can I determine whether my routes are vulnerable?
Check whether Traefik is running a version earlier than 2.11.55 and whether digestAuth middleware is configured on any routes. If both conditions apply, those digestAuth-protected routes should be treated as vulnerable.
What is the remediation?
Upgrade Traefik to version 2.11.55 or later. The provided information does not specify an alternative mitigation for deployments that cannot immediately upgrade.