Budibase: SSO OAuth2 Token Leakage via User Metadata Endpoints to Power-Role Users — @budibase / server
Exposure of Sensitive Information to an Unauthorized ActorSummary
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:
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):
controller.fetchMetadata→sdk.users.fetchMetadata()(packages/server/src/sdk/users/utils.ts:78)- →
getGlobalUsers()→getRawGlobalUsers()(packages/server/src/utilities/global.ts:101-122) — strips onlypasswordandforceResetPassword - →
processUser()(packages/server/src/utilities/global.ts:15-76) — strips onlypasswordandroles - The
oauth2field containingaccessTokenandrefreshTokenis never removed
Path 2 — Single user (GET /api/users/metadata/:id):
controller.findMetadata→getFullUser()(packages/server/src/utilities/users.ts:6)- →
getGlobalUser()→getRawGlobalUser()(packages/server/src/utilities/global.ts:90-92) — raw CouchDB fetch, no field stripping at all - →
processUser()— strips onlypasswordandroles - Same result:
oauth2tokens 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:
curl -s -X GET 'http://localhost:10000/api/users/metadata' \
-H 'Cookie: budibase:auth=<power-user-jwt>' \
-H 'x-budibase-app-id: app_<appid>' | jq '.[].oauth2'
Expected output: null for all users (tokens should not be exposed)
Actual output: For SSO users, the response includes:
{
"accessToken": "ya29.a0ARrdaM...",
"refreshToken": "1//0eXxXxXxXx..."
}
Step 2 — Fetch a specific SSO user's profile:
curl -s -X GET 'http://localhost:10000/api/users/metadata/ro_ta_users_us_<sso-user-id>' \
-H 'Cookie: budibase:auth=<power-user-jwt>' \
-H 'x-budibase-app-id: app_<appid>' | 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, anduserGroupsfields 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:
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.
| Software | From | Fixed in |
|---|---|---|
@budibase / server
|
- | 3.39.25 |
- https://github.com/Budibase/budibase/commit/7b8ba11a2c8b233c35e7728dd752dba25ef919a4
- https://github.com/Budibase/budibase/commit/80a31f6c3354620aa90e50af8a2c614333084621
- https://github.com/Budibase/budibase/pull/19110
- https://github.com/Budibase/budibase/releases/tag/3.39.25
- https://github.com/Budibase/budibase/security/advisories/GHSA-fcrw-f7gg-6g9f
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