Budibase: Missing Cache Invalidation on Public API Role Unassignment Allows Revoked Users to Retain Privileges for Up to 1 Hour

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Budibase is an open-source low-code platform. Prior to 3.38.2, the public API role unassignment endpoint (POST /api/public/v1/roles/unassign) updates user documents in CouchDB but does not invalidate the corresponding Redis user cache entries. Because the authentication middleware resolves user identity and permissions from this cache (TTL: 3600 seconds), a user whose admin, builder, or app-level roles have been revoked via the public API retains those privileges for up to 1 hour. This vulnerability is fixed in 3.38.2.

Source published

27 May 2026 17:05:21 UTC

Source modified

28 May 2026 14:08:42 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 4.2 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

Budibase is an open-source low-code platform. Prior to 3.38.2, the public API role unassignment endpoint (POST /api/public/v1/roles/unassign) updates user documents in CouchDB but does not invalidate the corresponding Redis user cache entries. Because the authentication middleware resolves user identity and permissions from this cache (TTL: 3600 seconds), a user whose admin, builder, or app-level roles have been revoked via the public API retains those privileges for up to 1 hour. This vulnerability is fixed in 3.38.2.

Source published

May 27, 2026, 5:05:21 PM (timezone not stated)

Source modified

May 28, 2026, 2:08:42 PM (timezone not stated)

Saved here

13 Nov 2026 13:05:54 UTC

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EUVD CVSS 3.1 · 4.2 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

Budibase is an open-source low-code platform. Prior to 3.38.2, the public API role unassignment endpoint (POST /api/public/v1/roles/unassign) updates user documents in CouchDB but does not invalidate the corresponding Redis user cache entries. Because the authentication middleware resolves user identity and permissions from this cache (TTL: 3600 seconds), a user whose admin, builder, or app-level roles have been revoked via the public API retains those privileges for up to 1 hour. This vulnerability is fixed in 3.38.2.

Source published

27 May 2026 18:16:26 UTC

Source modified

17 Jun 2026 10:53:39 UTC

Saved here

25 Oct 2026 12:17:14 UTC

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CVSS 3.1 · [email protected] · Secondary · 4.2 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

## Summary The public API role unassignment endpoint (`POST /api/public/v1/roles/unassign`) updates user documents in CouchDB but does not invalidate the corresponding Redis user cache entries. Because the authentication middleware resolves user identity and permissions from this cache (TTL: 3600 seconds), a user whose admin, builder, or app-level roles have been revoked via the public API retains those privileges for up to 1 hour. ## Details The root cause is an inconsistency between the `UserDB.save()` and `UserDB.bulkUpdate()` code paths. **Vulnerable path** — `packages/pro/src/sdk/publicApi/roles.ts:49-75`: ```typescript export async function unAssign(userIds: string[], opts: AssignmentOpts) { // ... modifies user objects: deletes roles, admin, builder ... await userDB.bulkUpdate(users) // line 74 } ``` `bulkUpdate` delegates to `bulkUpdateGlobalUsers()` at `packages/backend-core/src/users/users.ts:82-85`: ```typescript export async function bulkUpdateGlobalUsers(users: User[]) { const db = getGlobalDB() return (await db.bulkDocs(users)) as BulkDocsResponse } ``` This writes directly to CouchDB with **no cache invalidation**. **Correct path** — `packages/backend-core/src/users/db.ts:355` (used by admin UI): ```typescript await cache.user.invalidateUser(response.id) ``` **Cache configuration** — `packages/backend-core/src/cache/user.ts:11`: ```typescript const EXPIRY_SECONDS = 3600 // 1 hour TTL ``` **Authentication middleware** — `packages/backend-core/src/middleware/authenticated.ts:153-160`: ```typescript user = await getUser({ userId, tenantId: session.tenantId, email: session.email, }) ``` `getUser()` reads from Redis cache first; it only falls back to CouchDB on cache miss. After `unAssign` updates CouchDB without invalidating Redis, every authenticated request continues to use the stale cached user object with the old (revoked) privileges. Notably, other bulk operations in the codebase handle this correctly — `groups.addUsers()` and `groups.removeUsers()` in `packages/pro/src/sdk/groups/groups.ts` both loop through affected users and call `cache.user.invalidateUser()` after `bulkUpdateGlobalUsers()`. The public API roles path was missed. ## PoC ```bash # Prerequisites: Enterprise license, admin API key, a second user with admin role # Step 1: Confirm user has admin access curl -s -X GET http://localhost:10000/api/global/roles \ -H 'Cookie: budibase:auth=<target-user-session>' \ -H 'x-budibase-app-id: app_xyz' # Returns 200 with roles list # Step 2: Revoke admin role via public API curl -s -X POST http://localhost:10000/api/public/v1/roles/unassign \ -H 'x-budibase-api-key: <admin-api-key>' \ -H 'Content-Type: application/json' \ -d '{"userIds": ["<target-user-id>"], "admin": true}' # Returns 200 — role removed from CouchDB # Step 3: Verify DB was updated (admin field removed) # (check CouchDB directly - user document no longer has admin: {global: true}) # Step 4: Immediately retry admin endpoint as revoked user curl -s -X GET http://localhost:10000/api/global/roles \ -H 'Cookie: budibase:auth=<target-user-session>' \ -H 'x-budibase-app-id: app_xyz' # STILL returns 200 — stale cache serves old admin privileges # Step 5: Wait for cache expiry (up to 3600 seconds) and retry # After cache expires, the request correctly returns 403 ``` ## Impact A user whose admin, builder, or app-level roles have been revoked via the public API retains full access to those privileges for up to 1 hour. This is particularly concerning in automated offboarding scenarios where HR/IT systems use the public API to revoke access for terminated employees — the terminated user retains admin/builder access to all applications and data during the cache window. The impact is bounded by: - Requires enterprise license (expanded public API feature) - Maximum 1-hour window before cache expires - Only affects the public API revocation path; revocations via the admin UI (`UserDB.save()`) invalidate cache correctly - The `assign` direction has the inverse issue (newly granted roles are delayed) but this is less security-critical ## Recommended Fix Add cache invalidation to `bulkUpdateGlobalUsers` or to the callers that need it. The most targeted fix is in the `unAssign` function: ```typescript // packages/pro/src/sdk/publicApi/roles.ts import { cache } from "@budibase/backend-core" export async function unAssign(userIds: string[], opts: AssignmentOpts) { // ... existing role removal logic ... await userDB.bulkUpdate(users) // Invalidate cache for all affected users await Promise.all( users.map(user => cache.user.invalidateUser(user._id!)) ) } ``` Alternatively, fix it at the `bulkUpdate` level to prevent future callers from having the same gap: ```typescript // packages/backend-core/src/users/db.ts static async bulkUpdate(users: User[]) { const result = await usersCore.bulkUpdateGlobalUsers(users) await Promise.all( users.map(user => cache.user.invalidateUser(user._id!)) ) return result } ``` The same fix should also be applied to the `assign` function in the same file.

Source published

19 May 2026 16:30:38 UTC

Source modified

10 Sep 2026 03:50:45 UTC

Saved here

24 Oct 2026 13:17:17 UTC

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GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

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