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