Create 202512-01.md

Publish security advisory

Author: tvdijen

security/202512-01.md

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+---
+layout: default
+title: "SSPSA 202512-01: Signature bypass vulnerability"
+---
+
+<aside><div class="sidebar-warning right">
+<h2>Date</h2>
+08 December 2025
+<h2>Affected versions</h2>
+
+<code>SimpleSAMLphp 2.4.0 - 2.4.3</code><br/>
+<code>SimpleSAMLphp 2.3.0 - 2.3.9</code><br/>
+
+<code>Any older version</code><br/>
+<h2>Severity</h2>
+High - CVE 9.3
+</div></aside>
+
+# 202501-01
+
+**Signature bypass vulnerability**
+
+### Description
+
+An attacker could fabricate a SAML Response and the Service Provider would accept it, due to a bug in the libxml2-library.
+
+### Mitigation:
+
+Update to the latest version of SimpleSAMLphp, or manually bump the `robrichards/xmlseclibs` dependency to v3.1.4
+
+### Background / details
+
+https://portswigger.net/research/the-fragile-lock#golden-saml-response
+
+### Credit
+
+This vulnerability was discovered and reported by d0ge on December 2, 2025.
+It is registered under CVE-2025-66475.