CVE-2025-34291

CORS is a browser “rulebook” that tells websites which other sites they’re allowed to talk to. In Langflow versions up to 1.6.9, that rulebook is wrong, so an attacker can trick a user’s browser into handing over login access (token hijack), and then use that stolen access to run code on the server.

Think of it like leaving your office keycard reader set to accept keycards from the wrong door—then letting someone use that access to open the server room.

This matters if you run Langflow (self-hosted or otherwise exposed) and your Langflow version is 1.6.9 or older. The risk is tied to the vulnerable web behavior being reachable and usable over the network; findings indicate it is reachable in default configuration.

End-to-end risk is highest when the Langflow service is reachable from the internet or other untrusted networks without strong network access restrictions.

This is RED because it’s listed in CISA’s Known Exploited Vulnerabilities (KEV), meaning it’s known to be exploited in real environments. Attackers can hijack authentication tokens and then execute arbitrary code remotely, and this does not require a victim to take action.

Treat this as an immediate patch/mitigation task—upgrade to the fixed version without delay.