CVE-2026-33017

CVE-2026-33017 is a critical-severity (CVSS 9.8) vulnerability in Langflow Langflow. CISA added it to the Known Exploited Vulnerabilities catalog on March 25, 2026, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by April 8, 2026. CISA does not currently list it as used in ransomware campaigns. Langflow has 5 vulnerabilities in the KEV catalog, 1 of them linked to ransomware.

Langflow is a tool for building and deploying AI-powered agents and workflows. In versions prior to 1.9.0, the POST /api/v1/build_public_tmp/{flow_id}/flow endpoint allows building public flows without requiring authentication. When the optional data parameter is supplied, the endpoint uses attacker-controlled flow data (containing arbitrary Python code in node definitions) instead of the stored flow data from the database. This code is passed to exec() with zero sandboxing, resulting in unauthenticated remote code execution. This is distinct from CVE-2025-3248, which fixed /api/v1/validate/code by adding authentication. The build_public_tmp endpoint is designed to be unauthenticated (for public flows) but incorrectly accepts attacker-supplied flow data containing arbitrary executable code. This issue has been fixed in version 1.9.0.

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• https://github.com/advisories/GHSA-rvqx-wpfh-mfx7
• https://github.com/langflow-ai/langflow/commit/73b6612e3ef25fdae0a752d75b0fabd47328d4f0
• https://github.com/langflow-ai/langflow/security/advisories/GHSA-vwmf-pq79-vjvx
• https://github.com/langflow-ai/langflow/releases/tag/1.8.2
• https://medium.com/@aviral23/cve-2026-33017-how-i-found-an-unauthenticated-rce-in-langflow-by-reading-the-code-they-already-dc96cdce5896
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-33017
• https://www.sysdig.com/blog/cve-2026-33017-how-attackers-compromised-langflow-ai-pipelines-in-20-hours