What’s Vulnerable › Vulnerabilities

CVE-2026-49289: SimpleSAMLphp SAML2: Possible DoS via XPath Transform

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-19 · updated 2026-09-18
• Weakness: CWE-400

Description

The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. In 4.19.2 and 4.20.2, the library permits attacker-controlled XPath transforms while processing XML signatures in specially crafted SAML messages. XPath evaluation can consume uncontrolled processing resources, allowing a remote unauthenticated attacker to deny service to any entity relying on SimpleSAMLphp or directly on the SAML2 library. The mitigation limits the number of transforms, permits only transform algorithms identified by the SAML 2.0 Core specification, and specifically rejects XPath transforms. This issue is fixed in versions 4.19.3 and 4.20.3.

Affected products

• simplesamlphp saml2: from 4.19.2, < 4.19.3; from 4.20.2, < 4.20.3

References

• https://github.com/simplesamlphp/saml2/commit/0043033891fdba9618386ab583e1d8afdf8aea6e
• https://github.com/simplesamlphp/saml2/commit/6695eb923da491f716009c2a26b34a463ac05c6b
• https://github.com/simplesamlphp/saml2/security/advisories/GHSA-5cjr-mxj5-wmrx

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