{"id":"CVE-2026-33309","aliases":["GHSA-g2j9-7rj2-gm6c","PYSEC-2026-79"],"url":"https://o3.security/vulnerability/CVE-2026-33309","summary":"Langflow has an Arbitrary File Write (RCE) via v2 API","details":"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.","published":"2026-03-24T12:49:16.276Z","modified":"2026-08-12T03:51:21.967297485Z","cvss":{"score":9.9,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"},"epss":{"score":0.11064,"percentile":0.95543,"asOf":"2026-08-18"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"langflow","fixedVersion":"1.9.0"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33309.json"},{"type":"ADVISORY","url":"https://github.com/langflow-ai/langflow/security/advisories/GHSA-g2j9-7rj2-gm6c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33309"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:21.967297485Z"}}