PT-2026-42273 · Authentik · Authentik

Bugbunny-Research · Published 2026-05-20 · Updated 2026-05-25 · CVE-2026-40165

Positive Technologies (AI Summary)

CVSS v3.1

8.7

High

Base vector

AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions authentik versions prior to 2025.12.5 authentik versions 2026.2.0-rc1 through 2026.2.2

Description An authentication bypass exists due to SAML NameID XML Comment Injection. The software incorrectly extracts the NameID value from a SAML assertion, allowing an attacker to inject an XML comment that truncates the value. This enables an attacker with an account on a SAML Source and the ability to modify their NameID (such as a username or email) to gain access to other user accounts, provided that XML Signing is enabled.

Recommendations Update versions prior to 2025.12.5 to 2025.12.5. Update versions 2026.2.0-rc1 through 2026.2.2 to 2026.2.3.

Fix

Improper Authentication

Weakness Enumeration

CWE-91

CWE-287

CWE-436

Related Identifiers

BIT-AUTHENTIK-2026-40165

CVE-2026-40165

Affected Products

Authentik

References · 10

• https://nvd.nist.gov/vuln/detail/CVE-2026-40165 · Security Note
• https://osv.dev/vulnerability/BIT-authentik-2026-40165 · Vendor Advisory
• https://github.com/goauthentik/authentik/releases/tag/version%2F2025.12.5 · Note
• https://github.com/goauthentik/authentik/commit/47dec5c6b7fb4a62bfad2ae8bddf002bde7ba774 · Note
• https://github.com/goauthentik/authentik/security/advisories/GHSA-9wj8-xv4r-qwrp · Note
• https://reddit.com/r/pwnhub/comments/1tjn2uu/critical_authentication_bypass_vulnerability · Reddit Post
• https://twitter.com/CVEnew/status/2057407798690865296 · Twitter Post
• https://twitter.com/infoflowcloud/status/2057408803100905800 · Twitter Post
• https://t.me/CVEtracker/54450 · Telegram Post
• https://t.me/cveNotify/164319 · Telegram Post