CVE-2026-39839: Stored XSS through URLs in Cargo's map format

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-07 · updated 2026-07-24
Weakness: CWE-80

Description

Improper neutralization of Script-Related HTML tags in a web page (basic XSS) vulnerability in Wikimedia Foundation Mediawiki - Cargo Extension allows Stored XSS.This issue affects Mediawiki - Cargo Extension: before 3.8.7.

Affected products

The Wikimedia Foundation Mediawiki - Cargo extension: before 3.8.7 — fixed in 3.8.7

How to fix

Upgrade to a fixed version: The Wikimedia Foundation Mediawiki - Cargo extension 3.8.7. Check the vendor advisory for mitigations.

References

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Cargo/+/1237957
https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Cargo/+/1237977
https://phabricator.wikimedia.org/T416271

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