CVE-2025-27773: The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.17.0 and 5.0.0-alpha.20, there is a signature co...

Description

The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.17.0 and 5.0.0-alpha.20, there is a signature confusion attack in the HTTPRedirect binding. An attacker with any signed SAMLResponse via the HTTP-Redirect binding can cause the application to accept an unsigned message. Versions 4.17.0 and 5.0.0-alpha.20 contain a fix for the issue.

Metrics

CVSS 3.1

8.6/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

EPSS Probability

0.30%

21.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-347

References

Timeline

Published: Mar 11, 2025
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2025-27773?

The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.17.0 and 5.0.0-alpha.20, there is a signature confusion attack in the HTTPRedirect binding. An attacker with any signed SAMLResponse via the HTTP-Redirect binding can cause the application to accept an unsigned message. Versions 4.17.0 and 5.0.0-alpha.20 contain a fix for the issue.

How severe is CVE-2025-27773?

CVE-2025-27773 has a CVSS score of 8.6/10 (HIGH severity). The EPSS model estimates a 0.30% probability of exploitation in the next 30 days.

How do I fix CVE-2025-27773?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.