SimpleSAMLphp has Possible DoS via XPath Transform
Summary
This library turned out to be vulnerable to Denial-of-Service attacks using XPath transforms. A mitigation has been put in place to restrict the number of transforms and to restrict transforms to only the transform-algorithms mentioned in the SAML 2.0 Core Specifications (and specifically refuse XPath transforms).
Impact
An attacker is able to send specially crafted messages to any entity relying on SimpleSAMLphp (or directly on this SAML2-library) to be able to perform a Denial-of-Service attack.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | simplesamlphp/saml2 | >= 4.20.0, < 4.20.3, < 4.19.3 | 4.20.3, 4.19.3 |
| Composer package | simplesamlphp/saml2-legacy | >= 4.20.0, < 4.20.3, < 4.19.3 | 4.20.3, 4.19.3 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-400- Platform
- Composer
- Package
simplesamlphp/saml2, simplesamlphp/saml2-legacy- Disclosed
- 02.07.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-5cjr-mxj5-wmrx - CC BY 4.0
Vulnerability history: simplesamlphp/saml2-legacy
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 12.2024 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 3
- Medium 1
Disclosures per year
- 2024: 1
- 2025: 1
- 2026: 2
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SimpleSAMLphp has Possible DoS via XPath Transform this entry
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