CISA Warns of Active Exploitation: Critical Langflow RCE Vulnerability (CVE-2025-3248)

The Cybersecurity and Infrastructure Security Agency (CISA) has issued an urgent alert regarding an actively exploited remote code execution (RCE) vulnerability in Langflow, an open-source framework for building language model applications. Tracked as CVE-2025-3248 (CVSS 9.8), the flaw allows unauthenticated attackers to execute arbitrary code via Langflow’s /api/v1/validate/code endpoint. Federal agencies must patch by May 26, 2025, per CISA’s Binding Operational Directive (BOD 22-01)¹.

TL;DR: Key Takeaways

CVE-2025-3248: Unauthenticated RCE in Langflow’s API endpoint (CVSS 9.8).
Affected Versions: Langflow <1.3.0.
Exploit Status: Added to CISA’s Known Exploited Vulnerabilities (KEV) Catalog on May 5, 2025³.
Mitigation: Upgrade to Langflow 1.3.0+ and restrict API access.
PoC Available: Horizon3.ai disclosed a curl-based exploit².

Technical Analysis

The vulnerability stems from improper input validation in Langflow’s /api/v1/validate/code endpoint, which uses Python’s exec function to process untrusted user input. Attackers can craft malicious HTTP requests to execute arbitrary commands on vulnerable systems. Horizon3.ai’s disclosure includes a proof-of-concept (PoC) exploit leveraging this flaw²:

curl -X POST -H 'Content-Type: application/json' http://[target]/api/v1/validate/code -d '{"code": "@exec(\"raise Exception(__import__(\\\"subprocess\\\").check_output(\\\"env\\\"))\\\")\\\\ndef foo():\\\\n pass"}'

This exploit bypasses authentication and executes system commands via Python’s subprocess module. The flaw affects all Langflow versions prior to 1.3.0, which was released to address the issue³.

Mitigation and Response

CISA recommends immediate action for organizations using Langflow:

Patch: Upgrade to Langflow 1.3.0 or later.
Network Controls: Restrict public internet access to Langflow APIs.
Monitoring: Log and audit requests to /api/v1/validate/code.

Third-party tools like Horizon3.ai’s Nuclei template can detect vulnerable instances. CISA’s KEV entry emphasizes the urgency of remediation, noting active exploitation in the wild¹.

Broader Implications

This vulnerability highlights risks in AI/ML toolchains, particularly frameworks like Langflow that integrate with LangChain and LlamaIndex. Unauthenticated API flaws are increasingly targeted due to their ease of exploitation; VulnCheck reports 28.3% of Q1 2025 exploits occurred within 24 hours of disclosure⁶.

Similar vulnerabilities, such as SAP NetWeaver’s CVE-2025-31324 (unrestricted file upload), were also added to CISA’s KEV Catalog in April 2025⁵. The trend underscores the need for zero-trust policies in API authentication.

Conclusion

CVE-2025-3248 poses a critical threat to organizations using Langflow for language model applications. Immediate patching and network segmentation are essential to mitigate risks. For ongoing updates, monitor CISA’s KEV Catalog and vendor advisories.