CVE-2026-33309: Langflow has an Arbitrary File Write (RCE) via v2 API

March 19, 2026

While reviewing the recent patch for CVE-2025-68478 (External Control of File Name in v1.7.1), I discovered that the root architectural issue within LocalStorageService remains 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).

References

github.com/advisories/GHSA-g2j9-7rj2-gm6c
github.com/langflow-ai/langflow
github.com/langflow-ai/langflow/security/advisories/GHSA-g2j9-7rj2-gm6c
nvd.nist.gov/vuln/detail/CVE-2026-33309

Code Behaviors & Features

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