Is CVE-2026-100380 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-100380 being exploited in the wild.

How severe is CVE-2026-100380?

Informational severity, published 25 September 2026.

Which products and versions are affected?

Wikimedia Foundation MediaWiki before 1.46.1, 1.45.5, 1.43.10; Wikimedia Foundation Wikibase before 1.46.1, 1.45.5, 1.43.10.

Is there a fix for CVE-2026-100380?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-100380 attacked?

It is attacked over the network.

Am I affected by CVE-2026-100380?

Check whether you run Wikimedia Foundation MediaWiki or Wikimedia Foundation Wikibase 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-2026-100380: MediaWiki Wikibase reflected XSS in Special:SetLabel

CVE-2026-100380 · Severity: info · Published 2026-09-25

MediaWiki is a popular wiki engine that powers Wikipedia and other wikis. The Wikibase extension, which manages structured data in wikis, contains a cross-site scripting (XSS) vulnerability in the Special:SetLabel page where user-supplied language parameters are not properly sanitized. An attacker can craft a malicious link or form that, when visited by a wiki user, executes arbitrary JavaScript in the user's browser, potentially stealing credentials or session tokens.

Technologies: Wikimedia Foundation MediaWiki. Vendors: Wikimedia Foundation.

Quick answers

Is CVE-2026-100380 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-100380 being exploited in the wild.
How severe is CVE-2026-100380?: Informational severity, published 25 September 2026.
Which products and versions are affected?: Wikimedia Foundation MediaWiki before 1.46.1, 1.45.5, 1.43.10; Wikimedia Foundation Wikibase before 1.46.1, 1.45.5, 1.43.10.
Is there a fix for CVE-2026-100380?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-100380 attacked?: It is attacked over the network.
Am I affected by CVE-2026-100380?: Check whether you run Wikimedia Foundation MediaWiki or Wikimedia Foundation Wikibase 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 reflected XSS vulnerability exists in Special:SetLabel where language validation error messages fail to HTML-escape user input, allowing arbitrary script injection. The vulnerability is triggered via the language parameter and can be exploited by unauthenticated attackers through a crafted URL or HTML form without additional user interaction beyond visiting the page. The fix involves HTML-escaping error messages in the affected special pages (SetLabel and others).

Affected products

Wikimedia Foundation MediaWiki before 1.46.1, 1.45.5, 1.43.10
Wikimedia Foundation Wikibase before 1.46.1, 1.45.5, 1.43.10

Timeline

2026-08-11: disclosed
2026-09-25: disclosed

References

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