Description
authentik is an open-source identity provider. Prior to 2026.2.7, 2026.5.7, and 2026.8.2, an authentik SAML Source verifies an assertion's signature and validity period but does not ensure that the identity provider issued the assertion for that Source or in response to a login request from that Source. The SAML Source also does not record already accepted assertions, allowing replay. An unauthenticated actor who possesses such a valid assertion can use an assertion intended for another service provider or reuse an earlier assertion to authenticate as the user named by the assertion. Only SAML Sources are affected; SAML Providers and other Source types are not affected. This issue is fixed in versions 2026.2.7, 2026.5.7, and 2026.8.2.
References10
- docs.goauthentik.io/releases/2026.2#fixed-in-202627
- docs.goauthentik.io/releases/2026.5#fixed-in-202657
- docs.goauthentik.io/releases/2026.8#fixed-in-202682
- github.com/goauthentik/authentik/commit/287ea13cdc23c378abc20a7…
- github.com/goauthentik/authentik/commit/355d8cc3d755fbba05fc5fa…
- github.com/goauthentik/authentik/commit/54fac864a0b3bc00551af19…
- github.com/goauthentik/authentik/commit/984b0162711f0d1988ed335…
- github.com/goauthentik/authentik/pull/25957
- github.com/goauthentik/authentik/pull/25962
- github.com/goauthentik/authentik/pull/25967
Metrics
- CVSS 3.1
-
7.4
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS — exploit probability
- 0% percentile: 19 · as of 9 November 2026
- CWE
- CWE-287CWE-345
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.