CVE-2026-25739

CVE-2026-25739 is a medium-severity vulnerability in Cern Indico with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-25739?
CVE-2026-25739 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-25739 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25739?
CVE-2026-25739 affects Cern Indico. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25739?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-25739 have an EU (EUVD) identifier?
Yes. CVE-2026-25739 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8210.
When was CVE-2026-25739 published?
CVE-2026-25739 was published on 2026-02-19 and last updated on 2026-06-17.

References

Affected products (1)

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