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Vulnerability record · CVE-2026-40166 · published 22 May 2026

CVE-2026-40166: Information exposure vulnerability

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.

7.1 CVSS 4.0 High EPSS 0.56% · top 55.3% CWE-200 · Information exposureCWE-863 · Incorrect authorization Deferred
7.1CVSS 4.0 base score
0.56%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
23 Jul 2026Last modified by NVD

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:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

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

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Source: NIST National Vulnerability Database (record CVE-2026-40166), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.