Is CVE-2026-103443 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-103443 being exploited in the wild.

How severe is CVE-2026-103443?

Informational severity, published 30 September 2026.

Which products and versions are affected?

Wikimedia Foundation MediaWiki Collection 1.43, 1.45, 1.46.

Is there a fix for CVE-2026-103443?

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-2026-103443 attacked?

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

Am I affected by CVE-2026-103443?

Check whether you run Wikimedia Foundation MediaWiki Collection 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-2026-103443: MediaWiki Collection extension XSS via crafted javascript URL

CVE-2026-103443 · Severity: info · Published 2026-09-30

MediaWiki's Collection extension (used to compile articles into documents) contains a cross-site scripting vulnerability in its API endpoint. An attacker can inject a malicious javascript: URL into a victim's session without authentication, and when the victim opens the Book interface and clicks a "show article" link, arbitrary JavaScript executes in the wiki's security context. This allows attackers to steal data or perform actions on behalf of logged-in users.

Vendors: Wikimedia Foundation.

Quick answers

Is CVE-2026-103443 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-103443 being exploited in the wild.
How severe is CVE-2026-103443?: Informational severity, published 30 September 2026.
Which products and versions are affected?: Wikimedia Foundation MediaWiki Collection 1.43, 1.45, 1.46.
Is there a fix for CVE-2026-103443?: 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-2026-103443 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-103443?: Check whether you run Wikimedia Foundation MediaWiki Collection 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

The Collection extension's postcollection API endpoint (ApiPostCollection.php) accepts arbitrary JSON, stores it in the user's session without CSRF validation, and does not require authentication or POST method. The CollectionListTemplate later renders stored collection item URLs via htmlspecialchars() without validating the URL scheme, allowing javascript: URLs to remain executable. An attacker can seed a victim's session via an unauthenticated GET request; user interaction (clicking the show-article link) is required for exploitation.

Affected products

Wikimedia Foundation MediaWiki Collection 1.43, 1.45, 1.46

Timeline

2026-09-30: disclosed
2026-08-24: other: vulnerability reported

References

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