# CVE-2026-103438: MediaWiki Wikistories XSS in HTML tag sanitization

Source: https://junglewise.ai/threats/cve-2026-103438-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-2026-103438 · Severity: info · Published 2026-09-30

The Wikistories extension for MediaWiki fails to properly neutralize script-related HTML tags, allowing attackers to inject malicious JavaScript that executes in users' browsers. This cross-site scripting vulnerability could enable session hijacking, credential theft, or defacement of wiki content when users view pages containing the injected scripts.

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

## Quick answers

**Is CVE-2026-103438 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-103438 being exploited in the wild.

**How severe is CVE-2026-103438?** Informational severity, published 30 September 2026.

**Which products and versions are affected?** Wikimedia Foundation MediaWiki Wikistories 1.43, 1.45, 1.46.

**Is there a fix for CVE-2026-103438?** 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-2026-103438 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-103438?** Check whether you run Wikimedia Foundation MediaWiki Wikistories 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 is a basic reflected or stored XSS flaw in the Wikistories extension where script-related HTML tags are not properly sanitized before output. An attacker can inject arbitrary JavaScript through unfiltered input, which then executes in the context of other users' browsers. The vulnerability affects versions 1.43, 1.45, and 1.46 of the extension.

## Affected products

- Wikimedia Foundation MediaWiki Wikistories 1.43, 1.45, 1.46

## Timeline

- 2026-09-30: disclosed

## References

- [https://gerrit.wikimedia.org/r/q/Iad1281879723eba73e4338a00d5ff35c6eed0c3e](https://gerrit.wikimedia.org/r/q/Iad1281879723eba73e4338a00d5ff35c6eed0c3e)
- [https://phabricator.wikimedia.org/T182213](https://phabricator.wikimedia.org/T182213)