CVE-2025-59035: Cern Indico LaTeX XSS Vulnerability

CVE-2025-59035 Overview

CVE-2025-59035 is a stored Cross-Site Scripting (XSS) vulnerability in Indico, an open-source event management system developed by CERN. The flaw affects versions prior to 3.3.8 and occurs when the application renders LaTeX math code inside contribution or abstract descriptions. An authenticated user with content creation privileges can inject JavaScript that executes in the browsers of other users viewing the affected content. The vulnerability is tracked under CWE-79 and carries a CVSS 3.1 base score of 5.4.

Critical Impact
Attackers submitting crafted LaTeX content can execute arbitrary JavaScript in the browser context of event organizers and attendees, enabling session theft, phishing, and unauthorized actions on behalf of the victim.

Affected Products

CERN Indico versions prior to 3.3.8
Indico deployments running Call for Abstracts workflows that accept submissions from external contributors
Instances relying on Flask-Multipass authentication with LaTeX rendering enabled

Discovery Timeline

2025-09-10 - CVE-2025-59035 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-59035

Vulnerability Analysis

Indico allows users to include mathematical notation in contribution and abstract descriptions using LaTeX syntax. The rendering pipeline processes user-supplied LaTeX and outputs HTML for display. Prior to version 3.3.8, the sanitization layer did not fully neutralize markup produced during LaTeX-to-HTML conversion. A malicious submitter can craft LaTeX input that emits JavaScript into the rendered output.

The vulnerability is stored: the payload persists in the database and fires whenever a victim renders the affected contribution or abstract page. The exploit requires an authenticated account with submission rights and user interaction to view the content. Because the payload executes in the victim's authenticated session, the attacker inherits the victim's privileges within Indico.

The scope change reflected in the CVSS vector indicates that JavaScript executed in a victim browser can affect resources beyond the vulnerable component, including cookies, tokens, and cross-frame content served on the same origin.

Root Cause

The root cause is improper output encoding in the LaTeX math rendering path. The renderer accepted constructs that bypassed the surrounding sanitizer, allowing HTML and script elements to survive into the final DOM. This is a classic instance of CWE-79, Improper Neutralization of Input During Web Page Generation.

Attack Vector

An attacker registers or uses an existing Indico account, then submits an abstract or contribution containing a malicious LaTeX math expression. When a reviewer, organizer, or attendee views the submission, the injected script runs. In Call for Abstracts workflows, external speakers who are not fully trusted are explicitly invited to submit content, expanding the attack surface. See the Indico security advisory GHSA-7cf7-9wrr-vrf4 for the vendor description.

Detection Methods for CVE-2025-59035

Indicators of Compromise

Contribution or abstract records containing LaTeX blocks with <script>, onerror, onload, javascript:, or unusual HTML tags embedded inside math delimiters
Outbound HTTP requests from user browsers to unfamiliar domains shortly after loading an Indico contribution page
Unexpected session token or cookie access patterns originating from Indico page views

Detection Strategies

Query the Indico database for abstract and contribution descriptions containing HTML event handler attributes or <script substrings within math regions
Review web server access logs for repeated requests to abstract or contribution endpoints followed by anomalous third-party requests
Inspect Content Security Policy (CSP) violation reports for inline script or unauthorized script-source events on Indico pages

Monitoring Recommendations

Enable and centralize CSP reporting for the Indico origin to catch script injection attempts in real time
Log and alert on submissions from newly created external accounts that include LaTeX payloads exceeding normal size or complexity
Correlate reviewer session activity with unexpected privilege actions performed shortly after viewing a submission

How to Mitigate CVE-2025-59035

Immediate Actions Required

Upgrade Indico to version 3.3.8 or later, prioritizing instances running open Call for Abstracts workflows
Audit all abstracts and contributions submitted before the upgrade for embedded HTML or script content inside LaTeX blocks
Rotate session cookies and API tokens for accounts that may have viewed malicious submissions

Patch Information

The fix is included in Indico release v3.3.8. Administrators should follow the standard Indico upgrade procedure and restart the application workers after deployment. Full advisory details are available in GitHub Security Advisory GHSA-7cf7-9wrr-vrf4.

Workarounds

Restrict content creation to trustworthy, vetted users until the patch is applied
Temporarily disable or pause public Call for Abstracts workflows that accept submissions from unknown external speakers
Enforce a strict Content Security Policy that blocks inline scripts and restricts script sources on Indico pages

bash

# Upgrade Indico to the patched release
pip install --upgrade 'indico==3.3.8'
indico db upgrade
systemctl restart indico-uwsgi indico-celery