{"id":"GHSA-xxpx-f366-4xpq","title":"Craft CMS:Authorization bypass: view-only Categories user can modify category structure via structures/move-element","summary":"Craft CMS:Authorization bypass: view-only Categories user can modify category structure via structures/move-element","severity":"medium","cwe":["CWE-863"],"vendor":"craftcms","product":"craftcms/cms","ecosystem":"composer","affected":["craftcms/cms >= 5.0.0-RC1, < 5.10.6"],"patched":["craftcms/cms 5.10.6"],"published":"2026-08-06","updated":"2026-08-07","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-xxpx-f366-4xpq","references":[{"url":"https://github.com/craftcms/cms/security/advisories/GHSA-xxpx-f366-4xpq"},{"url":"https://github.com/craftcms/cms/commit/eb63721b8476ef53f21d7de53d156eef531cb57d"},{"url":"https://github.com/craftcms/cms/releases/tag/4.18.2"},{"url":"https://github.com/craftcms/cms/releases/tag/5.10.6"},{"url":"https://github.com/advisories/GHSA-xxpx-f366-4xpq"}],"tags":["ghsa","composer"],"ingestedAt":"2026-08-07T17:15:34.516Z","slug":"GHSA-xxpx-f366-4xpq","body":"## Overview\n\nA control-panel user who holds only the viewCategories permission for a category group (and not saveCategories) can permanently modify that group's category structure — reordering and re-parenting categories via the structures/move-element action.\n\nA read-time authorization grant that a write endpoint later trusts. For categories, the structureEditable flag is computed from the view permission (`src/elements/Category.php:205`) instead of the save permission (entries correctly use saveEntries — `src/elements/Entry.php:341`). When the read-only category index renders, `craft\\base\\Element::indexHtml()` calls `Craft::$app->getSession()->authorize('editStructure:<structureId>');` StructuresController then authorizes the structure-mutating action solely on that session grant, with no canSave re-check.\n\nVerified on Craft CMS 5.10.5. Same class as the moderate-severity authorization bypasses fixed in 5.10.3 and 5.10.5; this is a distinct, unpatched instance.\n\n## Impact\n\nA low-privileged, authenticated user (view-only on a category group) can persistently alter the sibling ordering and parent/child nesting of the category taxonomy. Because a category’s URI is derived from its position in the structure (ancestor slugs), moving a category changes its URL and the URLs of its descendants, and can corrupt any navigation/menus built from the category tree. This is an integrity/broken access-control issue: content that the user has no permission to modify is being modified. No confidentiality impact and no RCE; scope is content/taxonomy integrity.\n\n## Affected packages\n\n- `craftcms/cms >= 5.0.0-RC1, < 5.10.6`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `craftcms/cms 5.10.6`","depth":"sunlit","depthScore":28,"depthScoreParts":{"impact":27.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}