CVE-2026-39837 Stored XSS through the dynamic table format in Cargo

Medium 6.3 Published Updated

Stored XSS in MediaWiki Cargo Extension allows attackers to inject scripts via dynamic tables, potentially compromising user sessions.

Exploited in the wild
Not known
Login needed
Any signed-in user
Attackable
Over the internet
Victim action needed
A user has to click or open something
Fix
None listed

What is CVE-2026-39837?

CVE-2026-39837 is a medium-severity cross-site scripting vulnerability in Wikimedia Foundation Mediawiki - Cargo Extension, published on 7 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

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

Weakness: CWE-80

Which versions are affected by CVE-2026-39837?

It affects 1 product.

Products include Mediawiki Cargo.

How do I fix CVE-2026-39837?

No fix has been published for CVE-2026-39837 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-39837 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39837 exists.

Sources

Also known as GHSA-6m53-gpj2-w66j.

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