# CVE-2026-103437: MediaWiki ReadingLists reflected XSS in imported URLs

Source: https://junglewise.ai/threats/cve-2026-103437-improper-neutralization-of-script-related-html-tags-in-a-web  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-30. Updated: 2026-09-30  
License: CC BY 4.0 with a link back

CVE-2026-103437 · Severity: info · Published 2026-09-30

The Wikimedia Foundation's MediaWiki ReadingLists extension, which allows users to import reading lists from other wikis, contains a reflected cross-site scripting (XSS) vulnerability. An attacker can craft a malicious import link that executes arbitrary JavaScript in the victim's browser with their full MediaWiki session privileges, enabling account takeover, data theft, or unauthorized actions on their behalf.

Vendors: [Wikimedia Foundation](https://junglewise.ai/threats/vendors/wikimedia-foundation).

## Quick answers

**Is CVE-2026-103437 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103437 being exploited in the wild.

**How severe is CVE-2026-103437?** Informational severity, published 30 September 2026.

**Which products and versions are affected?** Wikimedia Foundation MediaWiki ReadingLists 1.45, 1.46.

**Is there a fix for CVE-2026-103437?** 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-2026-103437 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-103437?** Check whether you run Wikimedia Foundation MediaWiki ReadingLists 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 vulnerability exists in the web import flow where the extension accepts an attacker-controlled project URL and uses the canonicalurl returned by that server as a card link without validating its URI scheme. A named/authenticated user who opens a crafted Special:ReadingLists?limport= link and clicks the imported card will execute arbitrary JavaScript in the wiki origin. The fix requires validating imported URLs to allow only HTTP(S) schemes and rejecting javascript: or other non-standard URI schemes.

## Affected products

- Wikimedia Foundation MediaWiki ReadingLists 1.45, 1.46

## Timeline

- 2026-09-30: disclosed: Published on NVD and Wikimedia Phabricator

## References

- [https://gerrit.wikimedia.org/r/q/I9a724c05b2a55845007512422362e02ed8cf44b0](https://gerrit.wikimedia.org/r/q/I9a724c05b2a55845007512422362e02ed8cf44b0)
- [https://phabricator.wikimedia.org/T435863](https://phabricator.wikimedia.org/T435863)