CVE-2026-32600

simplesamlphp/xml-security: Missing AES-GCM Authentication Tag Validation on Encrypted Nodes Allows for Unauthorized Decryption

The general impact is:

XML nodes encrypted with AES-GCM can be decrypted by observing parsing differences
XML nodes encrypted with AES-GCM can be modified to decrypt to an arbitrary value
The GCM internal GHASH key can be recovered

In cases where the encryption key is embedded in the XML and is encrypted with the Service Provider's public key (like often done with SAML), the last two items don't have a big impact.
This is because:

With the Service Provider's public key, an arbitrary ciphertext can be created with a known symmetric key
The symmetric keys are generated on the fly every time the IdP creates a new SAMLResponse

In any case, secrets that are embedded in the XML, whether coming from an IdP, or from another scheme, can be decrypted.

Important: If static symmetric keys are used, as the GHASH key could have leaked, you must rotate those keys.

CVE-2026-32600 has a CVSS score of 8.2 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.3.1, 1.13.9); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

1. What is CVE-2026-32600? CVE-2026-32600 is a high-severity security vulnerability in simplesamlphp/xml-security (composer), affecting versions >= 2.0.0, < 2.3.1. It is fixed in 2.3.1, 1.13.9.
2. How severe is CVE-2026-32600? CVE-2026-32600 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of simplesamlphp/xml-security are affected by CVE-2026-32600? simplesamlphp/xml-security (composer) versions >= 2.0.0, < 2.3.1 is affected.
4. Is there a fix for CVE-2026-32600? Yes. CVE-2026-32600 is fixed in 2.3.1, 1.13.9. Upgrade to this version or later.
5. Is CVE-2026-32600 exploitable, and should I be worried? Whether CVE-2026-32600 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-32600 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-32600?
   • Upgrade simplesamlphp/xml-security to 2.3.1 or later
   • Upgrade simplesamlphp/xml-security to 1.13.9 or later

Other vulnerabilities in simplesamlphp/xml-security