What is the CVSS score of CVE-2026-25739?

CVE-2026-25739 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Github are affected by CVE-2026-25739?

Organizations using Indico should be aware of moderate risk from CVE-2026-25739, a cross-site scripting vulnerability rated CVSS 5.4.. A patch is available.

How to fix or mitigate CVE-2026-25739?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Github CVE-2026-25739

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-02-19 security-advisories@github.com

GHSA-jxc4-54g3-j7vp

Nginx Github Flask XSS Indico

5.4

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.4 MEDIUM

AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 22:03 vuln.today

Patch released

Feb 26, 2026 - 02:56 nvd

Patch available

CVE Published

Feb 19, 2026 - 16:27 nvd

MEDIUM 5.4

DescriptionGitHub Advisory

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.

AnalysisAI

Cross-site scripting in Indico prior to version 3.3.10 allows authenticated users to inject malicious scripts through material file uploads, potentially compromising other users' sessions or stealing sensitive data. The vulnerability affects Indico deployments using Flask-Multipass authentication and requires both user interaction and authenticated access to exploit. A patch is available, and administrators should upgrade to version 3.3.10 and update webserver configurations to enforce strict Content Security Policy for file downloads.

Technical ContextAI

Classified as CWE-79 (Cross-site Scripting (XSS)). Affects 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 I

RemediationAI

A vendor patch is available — apply it immediately. Update to version 3.3.10 or later. Implement output encoding and Content Security Policy headers. Restrict network access to the affected service where possible.