# CVE-2026-126564: Semantic MediaWiki stored XSS in ValueFormatter property label

Source: https://junglewise.ai/threats/cve-2026-126564-semantic-mediawiki-2-5-0-before-7-4-1-contains-a-stored-cross  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-11. Updated: 2026-11-11  
License: CC BY 4.0 with a link back

CVE-2026-126564 · Severity: medium · CVSS 5.4 · Published 2026-11-11

Semantic MediaWiki is a semantic layer for MediaWiki wikis that allows structured data queries and browsing. Users with page-edit permissions can inject malicious JavaScript into property labels that executes when administrators or other users view the Special:Browse page or use the smwbrowse API, potentially compromising admin accounts and stealing sensitive wiki data.

Technologies: [Semantic MediaWiki](https://junglewise.ai/threats/technologies/semantic-mediawiki). Vendors: [Semantic MediaWiki](https://junglewise.ai/threats/vendors/semantic-mediawiki).

## Quick answers

**Is CVE-2026-126564 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126564 being exploited in the wild.

**How severe is CVE-2026-126564?** Medium severity, with a CVSS score of 5.4, published 11 November 2026.

**Which products and versions are affected?** Semantic MediaWiki 2.5.0 before 7.4.1.

**Is there a fix for CVE-2026-126564?** Yes: fixed in 7.4.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-126564 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-126564?** Check whether you run Semantic MediaWiki 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.

## How to fix

- Fixed in 7.4.1

## Technical details

The ValueFormatter::getFormattedSubject() method splits formatted property labels on the first   to separate a user-supplied preferred label from the canonical property label suffix, but fails to escape the remainder before appending it as raw HTML. An attacker with edit rights can set a property label containing an img onerror payload and   sequences; when the label is split incorrectly, unescaped markup executes in the browsers of anyone viewing the property. The fix changes the split logic to target only the last  <span sequence, ensuring user-supplied text remains escaped by getLongHTMLText().

## Affected products

- Semantic MediaWiki Semantic MediaWiki 2.5.0 before 7.4.1

## Timeline

- 2026-11-11: disclosed

## References

- [https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/7.4.0/src/MediaWiki/Specials/Browse/ValueFormatter.php](https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/7.4.0/src/MediaWiki/Specials/Browse/ValueFormatter.php)
- [https://github.com/SemanticMediaWiki/SemanticMediaWiki/commit/c9bf9f25549bb2f5eab916339b267a1732002c4c](https://github.com/SemanticMediaWiki/SemanticMediaWiki/commit/c9bf9f25549bb2f5eab916339b267a1732002c4c)

## Related threats

- [Semantic MediaWiki authorization bypass in edit protection](https://junglewise.ai/threats/cve-2026-126566-semantic-mediawiki-7-3-1-before-7-4-1-contains-an-incorrect)
- [Semantic MediaWiki denial of service in concept expansion](https://junglewise.ai/threats/cve-2026-126565-semantic-mediawiki-3-0-0-before-7-4-1-contains-a-denial-of)
- [Semantic MediaWiki uncontrolled recursion in ConceptDescriptionInterpreter](https://junglewise.ai/threats/cve-2026-126562-semantic-mediawiki-3-0-0-before-7-4-1-contains-an-uncontrolled)
- [Semantic MediaWiki missing authorization in page edit protection](https://junglewise.ai/threats/cve-2026-126561-semantic-mediawiki-2-5-0-before-7-4-1-contains-a-missing)
- [Semantic MediaWiki stored cross-site scripting in DataTables](https://junglewise.ai/threats/cve-2026-126560-semantic-mediawiki-3-0-0-before-7-4-1-contains-a-stored-cross)