CVE-2025-3248

This flaw lets someone on the internet send a special request to your Langflow server that can cause the server to run code of the attacker’s choice. Think of it like leaving an “upload and run” door unlocked at your office—if it’s reachable, a bad actor can potentially break in and take control. The impact can include stealing data, shutting the service down, or being used as a launch point for ransomware.

This matters if your business runs Langflow (or the langflow-base component) and attackers can reach the /api/v1/validate/code endpoint. Because it is unauthenticated and can be triggered remotely without user interaction, it’s primarily a network-exposure problem rather than a “someone clicked something” problem. Treat it as a risk if the vulnerable endpoint is reachable from the internet (or otherwise reachable by untrusted users).

This is urgent because it is confirmed in CISA’s KEV list, meaning it has been recognized as a real, actively addressed threat. The vulnerability is unauthenticated and allows remote arbitrary code execution, and public exploits exist—so attackers do not need to first get a valid login. With a CISA remediation due date of 2025-05-26, you should treat this as a priority to remove exposure immediately.

1. Confirm exposure and versions

• Identify whether you run “Langflow” directly and what version is deployed.
• Also verify the langflow-base version that ships with/underpins your Langflow deployment.
• Confirm whether the service is reachable from untrusted networks (especially the public internet).

2. Determine if you are vulnerable

• Langflow is vulnerable if your version is before 1.3.0.
• langflow-base is vulnerable if your version is before 0.3.0.

3. Upgrade to the fixed versions (preferred remediation)

• Upgrade Langflow to 1.3.0 or later.
• Upgrade langflow-base to 0.3.0 or later (if applicable in your deployment/package).

4. Mitigation while patching (if upgrades are delayed)

• Ensure the /api/v1/validate/code endpoint is not accessible from the public internet.
• Restrict access at the network layer (firewall / reverse proxy rules) so only trusted callers can reach Langflow.
• Follow vendor-provided mitigation guidance referenced by the vendor remediation materials (as linked in the findings).

5. After upgrade

• Re-check that the deployed versions are truly the fixed ones.
• Validate that the /api/v1/validate/code endpoint is still functioning for legitimate use while remaining protected by your access controls.

6. Monitor for suspicious activity

• Look for unusual requests to /api/v1/validate/code (especially requests from unexpected IPs).
• Monitor for signs of server-side compromise (unexpected processes, new files, outbound connections) since the weakness is remote code execution.

Severity is critical, with the core issue being unauthenticated remote code execution (CWE-306, CWE-94) in Langflow’s /api/v1/validate/code endpoint. Attackers can send crafted HTTP requests that result in arbitrary code execution on the server. This is listed in CISA KEV (added 2025-05-05) with a remediation due date of 2025-05-26, indicating it has been recognized as a real-world threat requiring action. Public exploit availability is noted (two known public exploits), and the findings indicate exploitation readiness beyond simple proof-of-concept. A fix exists in langflow 1.3.0 and langflow-base 0.3.0; ensure you upgrade the components that match your deployment. (EPSS prediction was noted as very high, but KEV status and exploit availability are treated as the primary drivers of urgency.)