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CVE-2026-40166

authentik: Non-admin user can retrieve confidential OAuth client_secret via /api/v3/oauth2/access_tokens/

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 2025.12.5, 2026.2.3
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

authentik is an open-source identity provider. In versions prior to 2025.12.5 and 2026.2.0-rc1 through 2026.2.2, authenticated non-admin users with at least one OAuth2 access token can retrieve the client_secret of confidential OAuth2 providers they have previously authenticated against, exposing sensitive information to users without the correct permissions. This logic is GET /api/v3/oauth2/access_tokens/. The API response includes a nested provider object containing client_id and client_secret for providers configured with client_type: confidential, which should not be accessible to low-privilege users. This issue has been fixed in versions 2025.12.5 and 2026.2.3.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • goauthentik authentik

    fixed in 2025.12.5; From 2026.2.0-rc1 · fixed in 2026.2.3

References 3

GitHub · goauthentik/authentik