CVE-2026-126564 Semantic MediaWiki 2.5.0 before 7.4.1 Stored XSS via Special:Browse Factbox Title
Users with edit rights can store script in property labels that runs for anyone, including admins, viewing browse pages in Semantic MediaWiki.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Harmful if only installed
- No
- Needs a specific call
- No
- Fix
- None listed
What is CVE-2026-126564?
CVE-2026-126564 is a medium-severity cross-site scripting vulnerability in SemanticMediaWiki, published on 11 Nov 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Semantic MediaWiki 2.5.0 before 7.4.1 contains a stored cross-site scripting vulnerability in ValueFormatter::getFormattedSubject() that renders property label segments after a literal as unescaped markup. Users with page-edit rights can set a preferred property label containing an img onerror payload that executes when anyone, including administrators, views Special:Browse or the smwbrowse API.
Weakness: CWE-79
Which versions are affected by CVE-2026-126564?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-126564?
No fix has been published for CVE-2026-126564 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-126564 being exploited?
There is no known exploitation of CVE-2026-126564 in the wild and no public exploit code.
Sources
Also known as GHSA-mc5x-2j7v-x8hp, GHSA-pp7g-x87f-9vf5.