Langflow, an open-source visual framework for building LLM and agentic AI applications, contains a missing authentication flaw (CWE-306) in its /api/v1/validate/code endpoint. A remote attacker with network reachability to the endpoint can send crafted HTTP requests without any credentials, causing arbitrary code execution on the server. Successful exploitation yields code execution under the application's privileges, enabling data theft, backdoor installation, and, per CISA, ransomware deployment. Any running Langflow instance is affected; the tool is typically self-hosted by development teams building AI workflows, so real-world exposure depends on whether each instance is reachable from untrusted networks. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV catalog on 2025-05-05 with known ransomware use, EPSS assigns a 100% probability of exploitation within 30 days (100th percentile), and a public PoC is available.
What to do: Upgrade Langflow to the latest patched release identified in the vendor's advisory; federal agencies must apply mitigations per vendor instructions under BOD 22-01 or discontinue use if mitigations are unavailable. Until patched, restrict network access to the /api/v1/validate/code endpoint via reverse-proxy authentication, firewall rules, or VPN placement, and avoid exposing Langflow directly to the internet. Because ransomware use is confirmed, review access and process-execution logs for signs of prior compromise.
Affected
Langflow
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Estimated exposure
moderatetens of thousands of self-hosted deployments, with likely only hundreds to low thousands directly exposed to the internet — Langflow is a rapidly adopted open-source LLM builder typically deployed by developer teams for internal prototyping, so based on deployment patterns only a fraction of instances are expected to be internet-reachable; exact install and…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description
Langflow versions prior to 1.3.0 are susceptible to code injection in the /api/v1/validate/code endpoint. A remote and unauthenticated attacker can send crafted HTTP requests to execute arbitrary code.
CISA Known Exploited Vulnerability
Affected
Langflow Langflow
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
VulnCheck reports active exploitation of critical Langflow CVE-2026-0768 and Rails CVE-2026-66066 for credential harvesting, with detections rising to 360.
VulnCheck observed active exploitation of CVE-2026-0768 (CVSS 9.8) in Langflow and CVE-2026-66066 'KindaRails2Shell' (CVSS 9.5) in Ruby on Rails, with detections rising from 50 on August 30, 2026 to 360 by September 1. The Rails flaw allows unauthenticated arbitrary file reads, leaking secret_key_base, Rails master key, database passwords, cloud credentials and API tokens, ultimately enabling RCE; the patch still leaves the variation-key Marshal deserialization RCE gadget functional. Observed chains include a Python credential harvester with SimpleHelp remote access via CVE-2026-5027, and weaponization of CVE-2025-3248 to enlist hosts into an XMR mining botnet after disabling auditd. More than 7,100 exposed vulnerable Ruby on Rails instances and over 15,000 successful exploitation attempts across three Langflow flaws were recorded.