{"id":"GHSA-pw5q-rjx4-7f7p","summary":"Arcane: Delegated users:update permission allows admin account takeover via password reset (no privilege-hierarchy check)","details":"## Summary\nA user holding the delegated `users:update` permission can reset the global administrator's password and take over the admin account. `UpdateUser` sets the target user's `PasswordHash` from the request body for ANY target with no comparison of caller-vs-target privilege. Because role assignment and role CRUD are deliberately gated by `RequireGlobalAdmin`, `users:update` is intended to sit BELOW admin (profile management); this finding defeats that separation.\n\n## Root Cause\n`UpdateUser` (handler `backend/api/handlers/users.go:317-323`) loads the target by ID and sets `userModel.PasswordHash` from the request body for any user, then `userService.UpdateUser` (`user_service.go:174`) simply `tx.Save`s — with NO actor-vs-target privilege comparison. The only `IsGlobalAdmin` guard (`user_service.go:345`) is a last-admin check inside `DeleteUser`, not the update path. Role assignment / role CRUD are `RequireGlobalAdmin` (`backend/pkg/authz/permissions.go:27-33`), proving `users:update` is intended below admin.\n\n## Impact\nComplete administrator account takeover (C:H/I:H/A:H) by any holder of the delegated `users:update` permission.\n\n## Proof of Concept\n1. Admin delegates a custom \"User Manager\" role with `users:update`.\n2. `PUT /users/{adminId}` with `{\"password\":\"attacker123\"}`.\n3. `POST /auth/login {\"username\":\"arcane\",\"password\":\"attacker123\"}` → admin session.\n\n## Attack Chain\n1. Action: admin delegates custom role with `users:update`. Guard: role creation is `RequireGlobalAdmin`. Bypass: intended delegation (holder is meant to manage profiles, not seize admin).\n2. Action: `PUT /users/{adminId}` `{\"password\":\"attacker123\"}`. Guard: `RequirePermission(users:update)` (`users.go:154`). Bypass: holder has it; no hierarchy check (`users.go:317-323`, `user_service.go:174` unconditional Save).\n3. Action: `POST /auth/login` as admin → admin session.\n\n## Bypass Evidence\n- `users.go:317-323` sets `PasswordHash` for any target; `user_service.go:174-194` has no actor/target privilege comparison.\n- Only `IsGlobalAdmin` hits are `DeleteUser`'s last-admin guard and DTO flags (grep).\n- `users:update` is org-level, held by no built-in non-admin role (`permissions.go:24`).\n\n## Affected Versions\n`\u003c= 2.5.0`.\n\nReported by **zx (Jace)** — GitHub: @manus-use","aliases":["CVE-2026-96627"],"modified":"2026-10-16T21:30:04.583160239Z","published":"2026-10-16T21:15:03Z","database_specific":{"cwe_ids":["CWE-266","CWE-269"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-10-16T21:15:03Z","nvd_published_at":null},"references":[{"type":"WEB","url":"https://github.com/getarcaneapp/arcane/security/advisories/GHSA-pw5q-rjx4-7f7p"},{"type":"WEB","url":"https://github.com/getarcaneapp/arcane/pull/3426"},{"type":"WEB","url":"https://github.com/getarcaneapp/arcane/commit/21ea962f86d967dac8ae02a050f6e5f043d10fa1"},{"type":"PACKAGE","url":"https://github.com/getarcaneapp/arcane"},{"type":"WEB","url":"https://github.com/getarcaneapp/arcane/releases/tag/backend/v2.6.0"}],"affected":[{"package":{"name":"github.com/getarcaneapp/arcane/backend/v2","ecosystem":"Go","purl":"pkg:golang/github.com/getarcaneapp/arcane/backend/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.6.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-pw5q-rjx4-7f7p/GHSA-pw5q-rjx4-7f7p.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}