RCE in Langflow
CVE-2026-33309
Langflow is a tool for building and deploying AI-powered agents and workflows. Versions 1.2.0 through 1.8.1 have a bypass of the patch for CVE-2025-68478 (External Control of File Name), leading to the root architectural issue within `LocalStorageService` remaining unresolved. Because the underlying storage layer lacks boundary containment checks, the system relies entirely on the HTTP-layer `ValidatedFileName` dependency. This defense-in-depth failure leaves the `POST /api/v2/files/` endpoint vulnerable to Arbitrary File Write. The multipart upload filename bypasses the path-parameter guard, allowing authenticated attackers to write files anywhere on the host system, leading to Remote Code Execution (RCE). Version 1.9.0 contains an updated fix.
Vulnerability class: Path Traversal (Directory Traversal)
EPSS: 0.111 (95.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Langflow
- Langflow-ai Langflow — versions >= 1.2.0, < 1.9.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-33309?
- CVE-2026-33309 is a critical-severity vulnerability in Langflow, classified under Path Traversal. CVSS score: 9.9/10. Published 2026-03-24.
- How severe is CVE-2026-33309?
- Critical severity. CVSS v3 base score is 9.9 out of 10.