CVE-2026-77606 Semantic MediaWiki has reflected XSS in Special:Ask plain table headers
Attackers can execute arbitrary scripts via reflected XSS in Special:Ask plain table headers when the headers=plain setting is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-77606?
CVE-2026-77606 is a medium-severity cross-site scripting vulnerability in SemanticMediaWiki, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Semantic MediaWiki is a free, open-source extension to MediaWiki that lets users store and query data within the wiki's pages. Prior to version 7.2.0, when `headers=plain`, table header text was emitted into `<th>` via a raw HTML path. User-controlled `mainlabel` content could therefore become executable HTML. Version 7.2.0 fixes the issue.
Weakness: CWE-79
Which versions are affected by CVE-2026-77606?
2 open source packages ship an affected version, including mediawiki/semantic-media-wiki.
| Package | Affected | Fixed in |
|---|---|---|
mediawiki/semantic-media-wiki Packagist | All versions | 7.2.0 |
mediawiki/semantic-media-wiki Packagist | All versions | 7.2.0 |
How do I fix CVE-2026-77606?
Upgrade mediawiki/semantic-media-wiki to 7.2.0 or later.
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-2026-77606 being exploited?
There is no known exploitation of CVE-2026-77606 in the wild and no public exploit code.
Sources
Also known as GHSA-3jp5-3h47-28qf.