GHSA-fcrw-f7gg-6g9f Budibase: SSO OAuth2 Token Leakage via User Metadata Endpoints to Power-Role Users

• npm @budibase/server: < 3.39.25 → fixed in 3.39.25

Summary The `/api/users/metadata` and `/api/users/metadata/:id` endpoints in `@budibase/server` return full global user profiles to any user with POWER role or above. For SSO-authenticated users (OIDC, Google), the response includes `oauth2.accessToken` and `oauth2.refreshToken` fields, leaking identity provider credentials to other users who should not have access to them. Details When a user authenticates via SSO (OIDC or Google), the OAuth2 tokens are stored in the global CouchDB user document at `packages/backend-core/src/auth/auth.ts:170-173`: ```typescript dbUser.oauth2 = { ...dbUser.oauth2, ...details, } await db.put(dbUser) ``` The user metadata endpoints are protected by `PermissionType.USER, PermissionLevel.READ` (`packages/server/src/api/routes/user.ts:11`), which maps to the POWER permission set (`packages/backend-core/src/security/permissions.ts:99`). Path 1 — List all users (`GET /api/users/metadata`): 1. `controller.fetchMetadata` → `sdk.users.fetchMetadata()` (`packages/server/src/sdk/users/utils.ts:78`) 2. → `getGlobalUsers()` → `getRawGlobalUsers()` (`packages/server/src/utilities/global.ts:101-122`) — strips only `password` and `forceResetPassword` 3. → `processUser()` (`packages/server/src/utilities/global.ts:15-76`) — strips only `password` and `roles` 4. The `oauth2` field containing `accessToken` and `refreshToken` is never removed Path 2 — Single user (`GET /api/users/metadata/:id`): 1. `controller.findMetadata` → `getFullUser()` (`packages/server/src/utilities/users.ts:6`) 2. → `getGlobalUser()` → `getRawGlobalUser()` (`packages/server/src/utilities/global.ts:90-92`) — raw CouchDB fetch, no field stripping at all 3. → `processUser()` — strips only `password` and `roles` 4. Same result: `oauth2` tokens are returned There is no output sanitization middleware on these routes that would strip sensitive fields before the response reaches the client. PoC Prerequisites: A Budibase instance with at least one SSO-authenticated user (OIDC or Google) and a separate user with POWER role in an app. Step 1 — As the POWER user, list all users: ```bash curl -s -X GET 'http://localhost:10000/api/users/metadata' \ -H 'Cookie: budibase:auth=' \ -H 'x-budibase-app-id: app_' | jq '.[].oauth2' ``` Expected output: `null` for all users (tokens should not be exposed) Actual output: For SSO users, the response includes: ```json { "accessToken": "ya29.a0ARrdaM...", "refreshToken": "1//0eXxXxXxXx..." } ``` Step 2 — Fetch a specific SSO user's profile: ```bash curl -s -X GET 'http://localhost:10000/api/users/metadata/ro_ta_users_us_' \ -H 'Cookie: budibase:auth=' \ -H 'x-budibase-app-id: app_' | jq '.oauth2' ``` This also returns the full OAuth2 tokens. Impact • A user with POWER role in any app can read all SSO users' OAuth2 access tokens and refresh tokens via the list endpoint, without needing to know individual user IDs. • Stolen access tokens can be used to access external identity provider resources (Google Workspace, Azure AD, Okta-protected services) as the victim user. • Refresh tokens allow indefinite token renewal, persisting access even after the original access token expires. • Additionally, `admin`, `builder`, `tenantId`, `ssoId`, and `userGroups` fields are leaked, revealing the full authorization topology of the instance. Recommended Fix Strip sensitive SSO fields in `processUser()` at `packages/server/src/utilities/global.ts:15`: ```typescript export async function processUser( user: ContextUser, opts: { appId?: string; groups?: UserGroup[] } = {} ) { if (!user || (!user.roles && !user.userGroups)) { return user } user = cloneDeep(user) delete user.password + delete (user as any).oauth2 + delete (user as any).provider + delete (user as any).providerType + delete (user as any).thirdPartyProfile + delete (user as any).profile + delete (user as any).ssoId + delete (user as any).forceResetPassword // ... rest of function ``` Additionally, `getRawGlobalUsers()` at line 101 should also strip `oauth2` alongside its existing `password`/`forceResetPassword` stripping for defense in depth.