CVE-2026-39838: Wikimedia Foundation Mediawiki - Proofreadpage Extension

Medium severity, CVSS 6.9. EPSS: 0.5% chance of exploitation in the next 30 days.

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Wikimedia Foundation MediaWiki - ProofreadPage Extension allows XSS Targeting Non-Script Elements. The issue has been remediated on the `master` branch, and in the release branches for MediaWiki versions 1.43, 1.44, and 1.45.

Affected products

• Wikimedia Foundation Mediawiki - Proofreadpage Extension: before 1.43 (fixed in 1.43)

Published 2026-04-07. Last modified 2026-07-21.