authentik is an open-source identity provider. Prior to versions 2025.12.5, 2026.2.3, and 2026.5.1, authentik's SAML Source ACS endpoint is vulnerable to XML Signature Wrapping when validating upstream SAML responses. An attacker with any account at the upstream IdP can reuse a valid signed assertion to authenticate as another federated user.
This issue has been patched in versions 2025.12.5, 2026.2.3, and 2026.5.1.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 3
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Goauthentik Authentik
cpe:2.3:a:goauthentik:authentik:*:*:*:*:*:*:*:*
|
— |
2025.12.6
|
|
Goauthentik Authentik
cpe:2.3:a:goauthentik:authentik:*:*:*:*:*:*:*:*
|
2026.2.0
|
2026.2.4
|
|
Goauthentik Authentik
cpe:2.3:a:goauthentik:authentik:*:*:*:*:*:*:*:*
|
2026.5.0
|
2026.5.1
|