Medium · published September 18, 2026
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, `Special:URIResolver` resolves its user-controlled subpage to a MediaWiki title and issues an HTTP 303 redirect to `$title->getFullURL()` without validating the resolved target. A crafted subpage can make that target point off-host: an interwiki prefix redirects to the foreign wiki (for example `Special:URIResolver/mw-3AFoo`, which decodes to `mw:Foo`, redirects to `https://www.mediawiki.org/wiki/Foo`), and where the resolved URL carries an authority the target can even embed `user:pass@host` credentials. The result is an open redirect to an attacker-influenced host, usable for phishing from a trusted wiki URL. Version 7.2.0 fixes the issue.