CVE-2026-49289 is a high-severity uncontrolled resource consumption vulnerability in simplesamlphp/saml2 (composer), affecting versions <= 4.20.2. It is fixed in 4.20.3.
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.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
CVE-2026-49289 has a CVSS score of 7.5 (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 (4.20.3). Upgrading removes the vulnerable code path.
composer
simplesamlphp/saml2 (<= 4.20.2)simplesamlphp/saml2-legacy (<= 4.20.2)simplesamlphp/saml2 → 4.20.3 (composer)simplesamlphp/saml2-legacy → 4.20.3 (composer)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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 instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-49289 is reachable in your applications. Explore open-source security for your team.
See if CVE-2026-49289 is reachable in your applications. Get a demo
Already deployed Kodem? See CVE-2026-49289 in your environment →Upgrade the following packages to resolve this vulnerability:
simplesamlphp/saml2 to 4.20.3 or latersimplesamlphp/saml2-legacy to 4.20.3 or laterKodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-49289 is a high-severity uncontrolled resource consumption vulnerability in simplesamlphp/saml2 (composer), affecting versions <= 4.20.2. It is fixed in 4.20.3. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
CVE-2026-49289 has a CVSS score of 7.5 (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.
simplesamlphp/saml2 (composer) (versions <= 4.20.2)simplesamlphp/saml2-legacy (composer) (versions <= 4.20.2)Yes. CVE-2026-49289 is fixed in 4.20.3. Upgrade to this version or later.
Whether CVE-2026-49289 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
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.
simplesamlphp/saml2 to 4.20.3 or latersimplesamlphp/saml2-legacy to 4.20.3 or later