CVE-2025-27773

HIGH

Simplesamlphp Saml2 < 4.17.0 - Signature Verification Bypass

Title source: rule

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.

References (5)

[Mailing List] https://lists.debian.org/debian-lts-announce/2025/05/msg00013.html

[Vendor Advisory] https://github.com/simplesamlphp/saml2/security/advisories/GHSA-46r4-f8gj-xg56

[Patch] https://github.com/simplesamlphp/saml2/commit/7867d6099dc7f31bed1ea10e5bea159c5623d2a0

[Various Sources] https://github.com/simplesamlphp/saml2/blob/9545abd0d9d48388f2fa00469c5c1e0294f0303e/src/SAML2/HTTPRedirect.php#L104-L113

[Various Sources] https://github.com/simplesamlphp/saml2/blob/9545abd0d9d48388f2fa00469c5c1e0294f0303e/src/SAML2/HTTPRedirect.php#L178-L217

View Writeup ZIP pw:eip

Scores

CVSS v3 8.6

EPSS 0.0019

EPSS Percentile 40.4%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation poc

Automatable yes

Technical Impact partial

Details

CWE

CWE-347

Status published

Products (4)

simplesamlphp/saml2 0 - 4.17.0Packagist

simplesamlphp/saml2 < 4.17.0

simplesamlphp/saml2 >= 5.0.0-alpha.1, < 5.0.0-alpha.20

simplesamlphp/saml2-legacy 0 - 4.17.0Packagist

Published Mar 11, 2025

Tracked Since Feb 18, 2026