CVE-2025-27773highCWE-347

CVE-2025-27773: high-severity vulnerability in simplesamlphp saml2

SimpleSAMLphp SAML2 library has incorrect signature verification for HTTP-Redirect binding

Published · Updated

Follow this CVE+ Monitor saml2+ Monitor simplesamlphp

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 8.6epss 0.4%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Affected products
simplesamlphp · saml2
Related CVEs — simplesamlphp saml2

In the same product, most dangerous first.

CVE-2026-49289HIGHSimpleSAMLphp SAML2: Possible DoS via XPath TransformEPSS 0.8%CVE-2026-49283HIGHSimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypassEPSS 0.5%CVE-2024-52806HIGHSimpleSAMLphp SAML2 has an XXE in parsing SAML messagesEPSS 0.4%