SemanticMediaWiki versions 3.1.0 through 7.3.1 expose a reflected cross‑site scripting flaw when the unescaped default parameter in JsonResultPrinter is supplied in a query. An attacker can force a victim to click a specially crafted Special:Ask link containing a zero‑result query and request_type=special_page. The injected script executes in the wiki’s origin, allowing the attacker to read cookies, hijack the victim’s session, or perform malicious actions on behalf of the user. The flaw requires no authentication and is clear‑text based on the request URL.

SemanticMediaWiki by SemanticMediaWiki in the MediaWiki ecosystem, vulnerable in releases spanning 3.1.0 up to and including 7.3.1. Users running any of these versions without the fix are at risk whenever a specially crafted Special:Ask link is accessed.

The CVSS score of 5.3 indicates a medium severity vulnerability. No EPSS score is available, and the vulnerability is not listed in the CISA KEV catalog, suggesting that exploitation may rely on targeted social engineering rather than widespread, automated attacks. The likely attack vector involves sending or otherwise luring a user to a malicious link; once the victim follows the link, the injected JavaScript runs with the same privileges as the victim within the wiki context.