Summary
SimpleSAMLphp Reflected Cross-site Scripting vulnerability
Background
SimpleSAMLphp uses metadata to determine how to interact with other SAML entities. This metadata includes what’s called endpoints, which are URLs belonging to that entity where SAML messages can be sent. These URLs are used directly by SimpleSAMLphp when a message is sent, either via an HTTP redirection or by automatically posting a form to them.
Description
When sending a SAML message to another entity, SimpleSAMLphp will use the URL of the appropriate endpoint to redirect the user’s browser to it, or craft a form that will be automatically posted to it, depending on the SAML binding used. The URL that’s target of the message is fetched from the stored metadata for the given entity, and that metadata is trusted as correct.
However, if that metadata has been altered by a malicious party (either an attacker or a rogue administrator) to substitute the URLs of the endpoints with javascript code, SimpleSAMLphp was blindly using them without any validation, trusting the contents of the metadata. This would lead to a reflected XSS where the javascript code is sent inline to the web browser, and if SimpleSAMLphp is not using a strict Content Security Policy to forbid inline javascript (which is the case of the default user interface), then the code will be executed in the end user’s browser.
Affected versions
All SimpleSAMLphp versions are affected, up to 1.17.2.
Impact
If metadata is consumed for a rogue entity that includes javascript code in the corresponding endpoints, this javascript code might be run by users trying to access this entity.
Even though it’s unlikely that an administrator would add metadata for an entity that contains such endpoints inadvertently, if metadata is consumed automatically (e.g. using metarefresh) it would be easier to have an scenario like the one described here if a SAML entity is compromised and its metadata modified.
The severity is assessed as medium given the difficulty to exploit the issue.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
GHSA-VPR3-CW3H-PRW8 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. 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 (1.17.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is GHSA-VPR3-CW3H-PRW8? GHSA-VPR3-CW3H-PRW8 is a medium-severity cross-site scripting (XSS) vulnerability in simplesamlphp/simplesamlphp (composer), affecting versions >= 1.12.0, < 1.17.3. It is fixed in 1.17.3. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is GHSA-VPR3-CW3H-PRW8? GHSA-VPR3-CW3H-PRW8 has a CVSS score of 6.1 (Medium). 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.
- Which versions of simplesamlphp/simplesamlphp are affected by GHSA-VPR3-CW3H-PRW8? simplesamlphp/simplesamlphp (composer) versions >= 1.12.0, < 1.17.3 is affected.
- Is there a fix for GHSA-VPR3-CW3H-PRW8? Yes. GHSA-VPR3-CW3H-PRW8 is fixed in 1.17.3. Upgrade to this version or later.
- Is GHSA-VPR3-CW3H-PRW8 exploitable, and should I be worried? Whether GHSA-VPR3-CW3H-PRW8 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
- What actually determines whether GHSA-VPR3-CW3H-PRW8 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.
- How do I fix GHSA-VPR3-CW3H-PRW8? Upgrade
simplesamlphp/simplesamlphpto 1.17.3 or later.