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Medium · 6.1 CVE-2026-77610 EUVD-2026-83186GHSA-q5fm-9mx6-44f4

Semantic MediaWiki has a query debug output XSS (`DebugFormatter`)

Published Sep 18, 2026 · Updated Sep 21, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
SemanticMediaWiki SemanticMediaWiki < 7.2.0 —

Affected packages

EcosystemPackageAffectedFixedRecord
Packagist mediawiki/semantic-media-wiki < 7.2.0 7.2.0 GHSA-q5fm-9mx6-44f4

References