7.1

CVE-2026-40166: authentik: Non-admin user can retrieve confidential OAuth client_secret via /api/v3/oauth2/access_tokens/

Deferred
Published 22-05-2026Last modified 26-05-2026

Vulnerability summary

CVE-2026-40166 is a high (CVSS 7.1) vulnerability in goauthentik authentik. EPSS estimates a 0.46% chance of exploitation in the next 30 days, higher than 39.9% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 7.1, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.1/10
010
High · v4.0 (CVE.org)
EPSS score
0.46%
0%100%
Low · -0.10 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 22-05-2026
    PublishedVulnerability first disclosed.
  2. 26-05-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.46%

Chance of exploitation in the next 30 days

Percentile

40%

Versus all other CVEs

30-day change

Decrease -0.10 pp

From 0.56% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Goauthentik1 product
  • authentik< 2025.12.5 | ≥ 2026.2.0-rc1, < 2026.2.3

1 vendor · 1 product

References

3 links