ApostropheCMS: Same-parent page reorder in @apostrophecms/page move() re-ranks a restricted parent's children without create authorization

Impact

The attacker is an authenticated low-privileged user, an editor (or a contributor operating in draft mode), who holds edit rights on at least one ordinary page that is nested as a direct child of a restricted-type parent. No admin rights and no special tokens are required. Authorization in this CMS is resolved per page type, not per subtree: a page's editability is judged by its own type's editRole, so an ordinary public-page child can be editable by an editor even though its restricted secret-page-type parent (declaring editRole: admin) is not. Exploiting the gap, the editor can persistently alter the rank (sibling ordering, which drives navigation and menu order) of the restricted parent's other children, documents on which the editor holds no edit, create, publish, or delete authority. Repeating the reposition monotonically inflates those siblings' ranks. This is an integrity and authorization-boundary violation (CWE-862 / CWE-639) confined to sibling ordering; it does not disclose restricted field contents (confidentiality is unaffected) and it does not affect availability. The precondition (an editor-editable page already nested under a restricted parent) is a non-default tree state that an administrator establishes, or that arises from configuration drift when a page type gains a restricting editRole after editable children were already placed beneath it.

Proof of Concept

Dependencies: Node.js and a local MongoDB instance. The reproduction uses ApostropheCMS's own test harness to drive the real apos.page.move() code path with a non-admin editor request. No fresh end-to-end run was performed in the review environment (no MongoDB available); the chain was verified against source, and the sink behavior is independently corroborated by the CVE-2026-63669 advisory's own description and its cross-parent-only regression test.

1. Configure a restricted page type secret-page with editRole: 'admin' and publishRole: 'admin', and an ordinary type public-page with no role restriction.
2. As an admin, create a secret-page section under home, then create two secret-page children beneath it (the pre-existing restricted siblings), and place one editor-editable public-page as a further child of the secret section (the non-default nesting precondition).
3. As a non-admin editor, confirm the editor lacks _create/_edit on the secret section, then reposition the editable public-page among its siblings under the same secret parent.

// Same-parent reorder under a restricted parent, driven as a non-admin editor.
// The move must be forbidden but is not; the restricted siblings are re-ranked.
const editorReq = apos.task.getReq({
  role: 'editor',
  user: { _id: 'editor-user', title: 'Editor', role: 'editor' }
});

// `mine` is an editor-editable public-page already nested under the admin-only `secret` section.
// `secretChild` is a pre-existing admin-only sibling under the same `secret` parent.
const before = await apos.page.find(adminReq, { _id: secretChild._id }).toObject();

// Reposition `mine` to firstChild of its OWN current parent (secret) -> same-parent reorder.
await apos.page.move(editorReq, mine._id, secret._id, 'firstChild');

const after = await apos.page.find(adminReq, { _id: secretChild._id }).toObject();
console.log('secret child rank before:', before.rank, 'after:', after.rank);

Expected (secure) behavior: apos.page.move() throws "forbidden" for the editor.
Observed behavior (source-derived): move() succeeds; nudgeNewPeers() issues
updateMany({ ... rank: { $gte: 0 } }, { $inc: { rank: 1 } }) over the secret
section's children, so the admin-only sibling's rank changes (e.g. 0 -> 1)
even though the editor holds no edit/create rights on it.

Over HTTP the identical effect is reachable by a logged-in non-admin via PATCH /api/v1/@apostrophecms/page/<myPageId>:en:draft with body { "_targetId": "<sameParentId>:en:draft", "_position": "firstChild" } (also before/after a sibling), since the route reaches move() after only the page._edit gate on the moved page.

Attack Chain

1. Exposure: An authenticated editor sends PATCH (or PUT) /api/v1/@apostrophecms/page/<C> where C is an ordinary page the editor may edit, with body { _targetId: <P>, _position: 'firstChild' } and P is C's own current restricted parent. The route enforces only page._edit on the moved page C (index.js:1245 for patch, 619 for put).
2. Control: The attacker controls _targetId and _position. C's editability is resolved from C's own type via checkRoleConfig (permission/index.js:99-102, 114-122); an ordinary public-page passes for an editor regardless of the parent's type.
3. Path: move() resolves the target with getTarget() using .permission(false) (index.js:1873-1899), so no authorization is applied to the restricted parent P. determineRankAndNewParent() sets parent = target = P and getMoved() sets oldParent = P, so oldParent._id === parent._id.
4. Guard: The destination create guard (index.js:1684-1691) leads with (oldParent._id !== parent._id), which is false for the same-parent reorder, so the entire conditional short-circuits and parent._create is never checked. The moved-edit gate (index.js:1661) passes because the editor may edit C.
5. Primitive: nudgeNewPeers() (index.js:1781-1803) issues a raw self.apos.doc.db.updateMany that increments the rank of every direct child of P, including the restricted siblings, bypassing the per-document beforeUpdate edit check (doc-type/index.js:297-304).
6. Result: The editor persistently modifies the sibling ordering of documents under a restricted parent on which they hold no edit, create, publish, or delete authority, and can inflate those ranks arbitrarily by repeating the operation.

Bypass Evidence

This is an incomplete-fix follow-up to CVE-2026-63669 (GHSA-wr5r-wqp2-x4fh, published), whose fix restored the destination create guard in the same move() function. The prior fix and its regression test address only cross-parent moves; the same-parent reorder path was never covered.

• The guard condition at index.js:1684-1691 leads with (oldParent._id !== parent._id). For a same-parent reorder both identifiers are the same restricted parent, so the conjunct evaluates to false and the short-circuit skips the parent._create requirement. The guard's own inline comment scopes it to cross-parent moves. This holds both before and after the prior fix commit, which changed only the trailing archive-exception clause and left the leading cross-parent conjunct intact.
• The sink nudgeNewPeers() filters its updateMany only by path, level, aposLocale, and rank (index.js:1783-1792); there is no permission predicate, and because it calls the MongoDB driver directly it never triggers the @apostrophecms/doc-type:beforeUpdate per-document edit check (doc-type/index.js:297-304).
• The strongest refutation considered was that "reordering pages within a sibling group an administrator placed you in is intended behavior." It was rejected because the project's own model treats re-ranking a parent's children as a create-gated operation: insert() requires parent._create for every position (index.js:1436-1439) before its own peer nudge. The same-parent move() path is the sole route that performs the equivalent write without that check, and the modified siblings are outside the actor's authority.
• A second refutation, that a low-privileged editor could never legitimately hold an editable page under a restricted parent, was disproved: authorization is per type, not per subtree (checkRoleConfig reads only the doc's own type manager), so an editable public-page can exist as a child of a restricted secret-page parent. Post-fix an editor cannot create that nesting themselves (cross-parent move() and insert() both require parent._create), which confirms the precondition is administrator-established or the result of configuration drift, narrowing but not eliminating reachability.

Affected Versions

• Ecosystem: npm
• Package: apostrophe
• Confirmed affected range: <= 4.32.2
• Latest release checked: 4.32.2 (npm registry; npm view apostrophe version)
• Fix status: not fixed (no release addresses the same-parent reorder path)

The current published latest on npm is 4.32.2, and the same-parent reorder path is unguarded at that version (HEAD commit 46141d3, which stamps packages/apostrophe/package.json version 4.32.2). The prior fix for CVE-2026-63669 landed in the 4.32.0 line but only closed the cross-parent route, so the same-parent gap persists in the fixed line (an incomplete-fix window across 4.32.0 through 4.32.2) and, because the leading cross-parent conjunct predates that fix, in earlier releases as well. The introduction (lower) boundary was not pinned by inspecting each earlier released artifact; the decision-relevant, defensible statement is that the current 4.32.2 release is affected and no release fixes the same-parent path. Do not treat <= 4.32.2 as a proven lower-bounded range without inspecting earlier published artifacts.

Suggested Fix

Enforce destination authorization for the same-parent reorder path as well as for cross-parent moves. The invariant to restore is that re-ranking the children of a parent requires create (or, equivalently, the per-document authority the project uses for that boundary) on that parent, mirroring what insert() already enforces for every position. Concretely, evaluate the parent._create requirement independently of the (oldParent._id !== parent._id) condition, so that a same-parent reorder under a restricted parent is rejected when the actor lacks create on it; or gate nudgeNewPeers() itself on the actor's authority over the affected siblings rather than only on the cross-parent branch. Retaining the existing archive-restore exception is compatible with this change. Add a regression test that asserts a non-admin cannot reorder pages under a parent whose type carries a higher editRole/publishRole, complementing the existing cross-parent test. As an interim mitigation, operators can avoid nesting editor-editable pages beneath restricted-type parents and review such placements after any change that adds an editRole/publishRole to an existing page type.

Reported by zx (GitHub: @manus-pi).