CVE-2026-25739

Workarounds

• Use your webserver config to apply a strict CSP for material download endpoints.
• Only let trustworthy users create content (including material uploads, which speakers can typically do as well) on Indico.

For more information

If you have any questions or comments about this advisory:

• Open a thread in our forum
• Email us privately at [email protected]

There is a Cross-Site-Scripting vulnerability when uploading certain file types as materials.

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-2026-25739 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low 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 (3.3.10); upgrading removes the vulnerable code path.

Kodem intelligence

You should to update to Indico 3.3.10 as soon as possible.
See the docs for instructions on how to update.

Please be aware that to apply the fix itself updating is sufficient, but to benefit from the strict Content-Security-Policy we now apply by default for file downloads, you need to update your webserver config in case you use nginx with Indico's STATIC_FILE_METHOD set to xaccelredirect and add the following line to the .xsf/indico/ location block (you can consult the Indico setup documentation for the full configuration snippet):

add_header Content-Security-Policy $upstream_http_content_security_policy;

1. What is CVE-2026-25739? CVE-2026-25739 is a medium-severity cross-site scripting (XSS) vulnerability in indico (pip), affecting versions < 3.3.10. It is fixed in 3.3.10. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2026-25739? CVE-2026-25739 has a CVSS score of 5.4 (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 indico are affected by CVE-2026-25739? indico (pip) versions < 3.3.10 is affected.
4. Is there a fix for CVE-2026-25739? Yes. CVE-2026-25739 is fixed in 3.3.10. Upgrade to this version or later.
5. Is CVE-2026-25739 exploitable, and should I be worried? Whether CVE-2026-25739 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-2026-25739 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-2026-25739? Upgrade indico to 3.3.10 or later.