Langflow has an Arbitrary File Write (RCE) via v2 API

published 2026-03-19 7 mo ago modified 2026-06-17 4 mo ago also GHSA-g2j9-7rj2-gm6c , PYSEC-2026-79 , EUVD-2026-14788

cvss: 10.0; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 13.5%; EPSS 13.5% chance of exploitation in 30 days, percentile 96%
public exploits: 0; none known

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.

Patch / fix

fixed in 2

pypi langflow 1.9.0
langflow langflow 1.9.0

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 7 mo ago (2026-03-24)

Exploit prediction

13.47% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/langflow-ai/langflow/security/advisories/GHSA-g2j9-7rj2-gm6c referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	10.0	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
OSV	3.1	9.9	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
GitHub	3.1	9.9	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
pypi	langflow	>=1.2.0, <1.9.0	1.9.0

Affected products

langflow-ai langflow

Classification

Weakness

CWE-22 Improper Limitation of a Pathname to a Restricted Directory
CWE-73 External Control of File Name or Path
CWE-94 Improper Control of Generation of Code
CWE-284 Improper Access Control

References

github.com /langflow-ai/langflow/security/advisories/GHSA-g2j9-7rj2-gm6c
web, exploit, mitigation, vendor-advisory, evidence
nvd.nist.gov /vuln/detail/CVE-2026-33309
advisory
github.com /langflow-ai/langflow
package
github.com /pypa/advisory-database/tree/main/vulns/langflow/PYSEC-2026-79.yaml
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary