Is CVE-2026-39839 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-39839 being exploited in the wild.

How severe is CVE-2026-39839?

Medium severity, with a CVSS score of 6.1, published 7 April 2026.

Which products and versions are affected?

Wikimedia Foundation Cargo Extension before 3.8.7.

Is there a fix for CVE-2026-39839?

A patch was published on 2026-02-09: Fixes merged into master branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-39839 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-39839?

Check whether you run Wikimedia Foundation Cargo Extension at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-39839: Wikimedia MediaWiki Cargo Extension stored XSS in map format

CVE-2026-39839 · Severity: medium · CVSS 6.1 · Published 2026-04-07

The Cargo extension for MediaWiki, which allows for the storage and querying of structured data, contains a security flaw that allows for stored cross-site scripting (XSS). An attacker can inject malicious scripts into map-based data displays by using specially crafted links. If a user views the affected map and clicks on the malicious link, the script could execute in their browser, potentially leading to unauthorized actions or data theft.

Technologies: Wikimedia Foundation Cargo Extension. Vendors: Wikimedia Foundation.

Quick answers

Is CVE-2026-39839 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-39839 being exploited in the wild.
How severe is CVE-2026-39839?: Medium severity, with a CVSS score of 6.1, published 7 April 2026.
Which products and versions are affected?: Wikimedia Foundation Cargo Extension before 3.8.7.
Is there a fix for CVE-2026-39839?: A patch was published on 2026-02-09: Fixes merged into master branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-39839 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-39839?: Check whether you run Wikimedia Foundation Cargo Extension at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A stored cross-site scripting (XSS) vulnerability exists in the Cargo extension for MediaWiki due to improper neutralization of script-related HTML tags in the 'map' output format. Specifically, the extension fails to validate URLs used within map markers, allowing an attacker to store a 'javascript:' URI. When a user interacts with a marker containing this malicious link on a Cargo-generated map, the script executes in the context of the user's session. This issue is tracked as CWE-80 and was resolved in version 3.8.7 by adding URL validation to the CargoMapsFormat.php component.

Affected products

Wikimedia Foundation MediaWiki - Cargo Extension before 3.8.7

Timeline

2026-02-03: disclosed: Vulnerability reported via Phabricator task T416271
2026-02-09: patched: Fixes merged into master branch
2026-04-07: advisory: CVE-2026-39839 published

References

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