---
id: CVE-2026-39935
title: "Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in The Wikimedia Foundation Mediawiki - CampaignEvents Extension allows Cross-Site Scripting (XSS).\_This issue was remediated only on the …"
summary: "Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in The Wikimedia Foundation Mediawiki - CampaignEvents Extension allows Cross-Site Scripting (XSS).\_This issue was remediated only on the …"
severity: none
cwe:
  - CWE-79
published: '2026-04-07'
updated: '2026-07-21'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-39935'
references:
  - url: 'https://gerrit.wikimedia.org/r/c/1249320'
    label: c4f26cc8-17ff-4c99-b5e2-38fc1793eacc
  - url: 'https://phabricator.wikimedia.org/T418254'
    label: c4f26cc8-17ff-4c99-b5e2-38fc1793eacc
tags:
  - nvd
epss: 0.00453
epssPercentile: 0.36744
ingestedAt: '2026-07-22T07:59:32.581Z'
---

## Overview

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in The Wikimedia Foundation Mediawiki - CampaignEvents Extension allows Cross-Site Scripting (XSS). This issue was remediated only on the `master` branch.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.