{"id":"GHSA-cx86-7xwp-w9wf","summary":"Semantic MediaWiki affected by reflected XSS in `Special:Ask` via a forged cursor pagination token","details":"## 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]=\u003cforged token\u003e` where the token decodes to `{\"v\":1,\"sort_prop\":\"\u003cscript\u003e...\u003c/script\u003e\"}`. 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.","aliases":["CVE-2026-77616"],"modified":"2026-09-18T17:15:07.202492605Z","published":"2026-09-18T16:58:50Z","database_specific":{"cwe_ids":["CWE-79"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-09-18T16:58:50Z","nvd_published_at":null},"references":[{"type":"WEB","url":"https://github.com/SemanticMediaWiki/SemanticMediaWiki/security/advisories/GHSA-cx86-7xwp-w9wf"},{"type":"PACKAGE","url":"https://github.com/SemanticMediaWiki/SemanticMediaWiki"},{"type":"WEB","url":"https://github.com/SemanticMediaWiki/SemanticMediaWiki/releases/tag/7.2.0"}],"affected":[{"package":{"name":"mediawiki/semantic-media-wiki","ecosystem":"Packagist","purl":"pkg:composer/mediawiki/semantic-media-wiki"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.0.0"},{"fixed":"7.2.0"}]}],"versions":["7.0.0","7.1.0"],"database_specific":{"last_known_affected_version_range":"\u003c= 7.1.0","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-cx86-7xwp-w9wf/GHSA-cx86-7xwp-w9wf.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"}]}