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

Quick assessment

Affected
goauthentik authentik
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

authentik是authentik开源的一个身份提供应用程序。 authentik 2025.12.5之前版本和2026.2.0-rc1至2026.2.2版本存在安全漏洞，该漏洞源于GET /api/v3/oauth2/access_tokens/ API响应包含嵌套的provider对象，其中包含client_secret，可能导致敏感信息泄露。

AI Predicted 5.3 Difficulty: Easy EPSS 0.46% · P38

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage

Affected Version Matrix 2

VendorProduct Version RangeStatus
goauthentik authentik < 2025.12.5 affected
>= 2026.2.0-rc1, < 2026.2.3 affected
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I. Basic Information for CVE-2026-40166

Vulnerability Information
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Vulnerability Title
authentik: Non-admin user can retrieve confidential OAuth client_secret via /api/v3/oauth2/access_tokens/
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
authentik 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
authentik是authentik开源的一个身份提供应用程序。 authentik 2025.12.5之前版本和2026.2.0-rc1至2026.2.2版本存在安全漏洞，该漏洞源于GET /api/v3/oauth2/access_tokens/ API响应包含嵌套的provider对象，其中包含client_secret，可能导致敏感信息泄露。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
goauthentik authentik < 2025.12.5 -

II. Public POCs for CVE-2026-40166

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III. Intelligence Information for CVE-2026-40166

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Vendor Advisories for CVE-2026-40166 (1)

Vendor Pages for CVE-2026-40166 (1)

Other References for CVE-2026-40166 (1)

IV. Related Vulnerabilities

Same product: authentik
Same vendor: goauthentik
Same weakness: CWE-200

V. Comments for CVE-2026-40166

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