CVE-2025-34291

Langflow versions up to and including 1.6.9 contain a chained vulnerability that enables account takeover and remote code execution. An overly permissive CORS configuration (allow_origins='*' with allow_credentials=True) combined with a refresh token cookie configured as SameSite=None allows a malicious webpage to perform cross-origin requests that include credentials and successfully call the refresh endpoint. An attacker-controlled origin can therefore obtain fresh access_token / refresh_token pairs for a victim session. Obtained tokens permit access to authenticated endpoints — including built-in code-execution functionality — allowing the attacker to execute arbitrary code and achieve full system compromise.

Attacker registers a domain and hosts a malicious webpage containing JavaScript that silently fetches the victim organization's Langflow refresh endpoint (e.g., https://langflow.company.com/api/v1/refresh). Because Langflow is misconfigured with allow_origins='*' plus allow_credentials=True, and the refresh cookie carries SameSite=None, the browser automatically includes the victim's cookie in the cross-origin request. The server responds with a fresh access_token/refresh_token pair. The attacker's script immediately uses the stolen access token to call Langflow's code execution endpoint, running a Python reverse shell. The attacker now has persistent RCE, extracts LLM API keys from environment variables, and pivots to connected AI infrastructure — all without the victim performing any action beyond loading the malicious page while authenticated to Langflow.