CVE-2025-65954

The logout endpoint accepts a url query parameter to redirect to. casserver treats that url as trusted, and either (depending on configuration) redirects the browser there, or shows a "you've been logged out" page with a link to continue to that url.

There are a number of other things broken with logout in 7 (cas v3 uses a different query parameters, etc)

Details

https://github.com/simplesamlphp/simplesamlphp-module-casserver/blob/21418f7efbea8c4f078fd4a7d1b9eacf94dd4941/src/Controller/LogoutController.php#L104

Previous module checked the url against the valid service urls.

PoC

The docker instructions from the README.md run an image with a vulnerable config.

Accessing https://localhost/cas/logout?url=https://google.com will redirect to Google

Impacted configs have

'enable_logout' => true,

and are most impacted if they also have

'skip_logout_page' -> true,

Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites. Typical impact: phishing and credential harvesting via a trusted domain.

CVE-2025-65954 has a CVSS score of 4.7 (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 (7.0.0, 6.3.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2025-65954? CVE-2025-65954 is a medium-severity open redirect vulnerability in simplesamlphp/simplesamlphp-module-casserver (composer), affecting versions >= 7.0.0-rc1, < 7.0.0-rc3. It is fixed in 7.0.0, 6.3.1. Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites.
2. How severe is CVE-2025-65954? CVE-2025-65954 has a CVSS score of 4.7 (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.
3. Which versions of simplesamlphp/simplesamlphp-module-casserver are affected by CVE-2025-65954? simplesamlphp/simplesamlphp-module-casserver (composer) versions >= 7.0.0-rc1, < 7.0.0-rc3 is affected.
4. Is there a fix for CVE-2025-65954? Yes. CVE-2025-65954 is fixed in 7.0.0, 6.3.1. Upgrade to this version or later.
5. Is CVE-2025-65954 exploitable, and should I be worried? Whether CVE-2025-65954 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-2025-65954 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-2025-65954?
   • Upgrade simplesamlphp/simplesamlphp-module-casserver to 7.0.0 or later
   • Upgrade simplesamlphp/simplesamlphp-module-casserver to 6.3.1 or later