CVE-2026-77610 Semantic MediaWiki has a query debug output XSS (`DebugFormatter`)
Reflected XSS in Semantic MediaWiki allows attackers to execute arbitrary scripts via unescaped query debug output, requiring no special privileges.
- 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-2026-77610?
CVE-2026-77610 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, query debug output (`format=debug`, or the `debug` request parameter on `Special:Ask`) is assembled by `SMW\Query\DebugFormatter` and emitted as raw HTML. Several of its sinks apply no output-context encoding, so attacker-controlled query input is reflected into the page without escaping. On `Special:Ask` the resulting string is concatenated into the page and sent through `OutputPage::addHTML`, never through the MediaWiki parser or Sanitizer. No special user right is required; an anonymous request suffices. This is a reflected XSS: the payload is taken from the request and echoed in the same response. Exploitation requires the query condition to target a text/blob-typed property (whose value is re-serialized verbatim); the predefined `_txt` properties (`Text`, etc.) that ship on every install satisfy this, so no attacker-created content is needed. Version 7.2.0 patches the issue.
Weakness: CWE-79
Which versions are affected by CVE-2026-77610?
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-2026-77610?
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-2026-77610 being exploited?
There is no known exploitation of CVE-2026-77610 in the wild and no public exploit code.
Sources
Also known as GHSA-q5fm-9mx6-44f4.