CVE-2026-77616

Medium CVSS 6.1

Published 2026-09-18 · last changed 2026-09-18

The fix

We hold no Microsoft remediation data for CVE-2026-77616, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

Semantic MediaWiki is a free, open-source extension to MediaWiki that lets users store and query data within the wiki's pages. In versions 7.0.0 through 7.1.0, `Special:Ask` accepts a `cursor` query parameter for keyset pagination (added in 7.0.0). The token is decoded by `CursorEncoder`, which is an **unsigned** base64url-encoded JSON blob, so its contents are fully attacker-controlled. When the cursor's sort anchor does not match the request's `sort=` / `order=`, `QueryCreator::applyCursorIfRequested()` builds an error message by interpolating the attacker-controlled `sort_prop` / `sort_order` values into a raw string via `Query::addErrors()`. Unlike SMW's message-key errors, this raw string bypasses the message layer's sanitization (`ProcessingErrorMsgHandler::normalizeAndDecodeMessages()` passes a non-key, non-encoded string through unchanged). `ErrorWidget::queryError()` then assembles the errors and passes them to `Html::errorBox()`, whose first argument is emitted as raw HTML. The result is a reflected cross-site scripting vulnerability: a crafted `cursor` token containing markup in `sort_prop` (or `sort_order`) executes script in the victim's browser on the wiki origin. No authentication or special permission is required. The payload is delivered via a crafted link. Version 7.2.0 contains a fix.

Sources

NVD record for CVE-2026-77616

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N