Public proof of conceptFix available

CVE-2026-33309

Q: Is CVE-2026-33309 actively exploited?

A proof-of-concept exploit exists for CVE-2026-33309, but active exploitation has not been confirmed at this time.

Q: What is the CVSS score for CVE-2026-33309?

CVE-2026-33309 has a CVSS v3 base score of 9.9 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

A public proof of concept exists; no exploitation attested.

Published2026-03-24
Fixed in1.9.0
WeaknessCWE-22 · CWE-284 · CWE-73

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2026-03-2413:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-33309?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-33309?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Langflow

Branch	Affected	Fixed in	Source
1.x	≥ 1.2.0, < 1.9.0	1.9.0	NVD · OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Langflow to 1.9.0

Advisories and patches

github.comMitigation · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionpoc2026-03-24
OpenCVESSVC decisionpoc—
CNACVSS 3.19.9read 2026-10-23
CNAweakness (CWE)CWE-22, CWE-284, CWE-73, CWE-94read 2026-10-23
FIRST EPSSEPSS score1.1 %2026-10-22
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Published: 2026-03-24
Last Modified: 2026-06-17
NVD status: Analyzed

Frequently asked questions

What is CVE-2026-33309?

Is CVE-2026-33309 actively exploited?

A proof-of-concept exploit exists for CVE-2026-33309, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-33309?

CVE-2026-33309 has a CVSS v3 base score of 9.9 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

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