{"id":"GHSA-cx86-7xwp-w9wf","aliases":["CVE-2026-77616"],"title":"Semantic MediaWiki affected by reflected XSS in `Special:Ask` via a forged cursor pagination token","description":"## Reflected XSS via a forged cursor pagination token\n\n#### Failure mode\n\n`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()`.\n\nUnlike SMW's message-key errors, this raw string bypasses the message layer's sanitisation (`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.\n\nNo authentication or special permission is required. The payload is delivered via a crafted link, e.g. `Special:Ask?q=...&p[cursor]=<forged token>` where the token decodes to `{\"v\":1,\"sort_prop\":\"<script>...</script>\"}`. Confirmed executing in a browser; the responses carry no Content-Security-Policy, so inline script is not blocked.\n\n#### Remediation\n\n- Output-encode the attacker-controlled `sort_prop` / `sort_order` values before they are interpolated into the error text in `QueryCreator`, so no raw user input enters the error stream.\n- Defense in depth: the `format=debug` output path that reflected the same error text was hardened separately in GHSA-q5fm-9mx6-44f4.\n\n#### Maintenance note\n\nQuery error strings are rendered as raw HTML by `ErrorWidget::queryError()` via `Html::errorBox()`. Any error added through `Query::addErrors()` that embeds user-controlled text must be output-encoded (or use a message key); pagination and validation error text is attacker-influenced and must not be treated as trusted.","severity":"medium","score":6.1,"published":"2026-09-18T16:58:50.000Z","modified":"2026-09-18T17:15:05.477Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Packagist","name":"mediawiki/semantic-media-wiki","ranges":[{"events":[{"introduced":"7.0.0"},{"fixed":"7.2.0"}],"type":"ECOSYSTEM"}],"versions":["7.0.0","7.1.0"],"fixed":["7.2.0"]}],"sourceAffected":[],"references":["https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-cx86-7xwp-w9wf","https://github.com/SemanticMediaWiki/SemanticMediaWiki","https://github.com/SemanticMediaWiki/SemanticMediaWiki/releases/tag/7.2.0"],"sources":[{"name":"OSV","id":"GHSA-cx86-7xwp-w9wf","modified":"2026-09-18T17:15:05.477969486Z","url":"https://osv.dev/vulnerability/GHSA-cx86-7xwp-w9wf"}],"assessments":[{"source":"OSV","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1}]}