CVE-2026-25739

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Versions prior to 3.3.10 are vulnerable to cross-site scripting when uploading certain file types as materials. Users should upgrade to version 3.3.10 to receive a patch. To apply the fix itself updating is sufficient, but to benefit from the strict Content Security Policy (CSP) Indico now applies by default for file downloads, update the webserver config in case one uses nginx with Indico's STATIC_FILE_METHOD set to xaccelredirect. For further directions, consult the GitHub Security advisory or Indico setup documentation. Some workarounds are available. Use the webserver config to apply a strict CSP for material download endpoints, and/or only let trustworthy users create content (including material uploads, which speakers can typically do as well) on Indico.

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Versions prior to 3.3.10 are vulnerable to cross-site scripting when uploading certain file types as materials. Users should upgrade to version 3.3.10 to receive a patch. To apply the fix itself updating is sufficient, but to benefit from the strict Content Security Policy (CSP) Indico now applies by default for file downloads, update the webserver config in case one uses nginx with Indico's STATIC_FILE_METHOD set to xaccelredirect. For further directions, consult the GitHub Security advisory or Indico setup documentation. Some workarounds are available. Use the webserver config to apply a strict CSP for material download endpoints, and/or only let trustworthy users create content (including material uploads, which speakers can typically do as well) on Indico.

Impact

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

Patches

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;

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]

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Versions prior to 3.3.10 are vulnerable to cross-site scripting when uploading certain file types as materials. Users should upgrade to version 3.3.10 to receive a patch. To apply the fix itself updating is sufficient, but to benefit from the strict Content Security Policy (CSP) Indico now applies by default for file downloads, update the webserver config in case one uses nginx with Indico's STATIC_FILE_METHOD set to xaccelredirect. For further directions, consult the GitHub Security advisory or Indico setup documentation. Some workarounds are available. Use the webserver config to apply a strict CSP for material download endpoints, and/or only let trustworthy users create content (including material uploads, which speakers can typically do as well) on Indico.

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Versions prior to 3.3.10 are vulnerable to cross-site scripting when uploading certain file types as materials. Users should upgrade to version 3.3.10 to receive a patch. To apply the fix itself updating is sufficient, but to benefit from the strict Content Security Policy (CSP) Indico now applies by default for file downloads, update the webserver config in case one uses nginx with Indico's STATIC_FILE_METHOD set to xaccelredirect. For further directions, consult the GitHub Security advisory or Indico setup documentation. Some workarounds are available. Use the webserver config to apply a strict CSP for material download endpoints, and/or only let trustworthy users create content (including material uploads, which speakers can typically do as well) on Indico.

Impact

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

Patches

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;

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]

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Versions prior to 3.3.10 are vulnerable to cross-site scripting when uploading certain file types as materials. Users should upgrade to version 3.3.10 to receive a patch. To apply the fix itself updating is sufficient, but to benefit from the strict Content Security Policy (CSP) Indico now applies by default for file downloads, update the webserver config in case one uses nginx with Indico's STATIC_FILE_METHOD set to xaccelredirect. For further directions, consult the GitHub Security advisory or Indico setup documentation. Some workarounds are available. Use the webserver config to apply a strict CSP for material download endpoints, and/or only let trustworthy users create content (including material uploads, which speakers can typically do as well) on Indico.