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LangflowApplication

CVE-2026-33309

CRITICAL · 9.9 CVSS v3.1 Published 2026-03-24
Fix available
A fix is available. Upgrade to 1.9.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Langflow versions 1.2.0-1.8.1 contain a patch bypass for CVE-2025-68478 where the LocalStorageService lacks boundary containment checks entirely, relying only on HTTP-layer ValidatedFileName validation. The POST /api/v2/files/ endpoint allows authenticated attackers to bypass path-parameter guards via multipart upload filename manipulation, achieving Arbitrary File Write leading to RCE.

MitigationUpgrade to Langflow version 1.9.0 which contains the updated fix. If unable to upgrade immediately, restrict authenticated access to the file upload endpoint and implement network-level controls.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
LangflowApplication
Affected:>= 1.2.0, < 1.9.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Langflow version
    Run 'pip show langflow' or check the version via the API health endpoint
    Affected if Version is 1.2.0 through 1.8.1 (or any version below 1.9.0)
  2. Confirm the /api/v2/files endpoint is exposed
    Attempt a POST request to /api/v2/files/ on the Langflow server (may require authentication)
    Affected if The endpoint responds and accepts multipart file uploads
  3. Verify LocalStorageService boundary configuration
    Inspect the LocalStorageService configuration for any path containment or sandboxing settings
    Affected if No boundary containment checks are configured, relying solely on HTTP-layer ValidatedFileName validation
  4. Test if authenticated file upload allows filename manipulation
    Send a multipart upload request with a manipulated filename parameter (e.g., ../../../etc/passwd)
    Affected if The upload succeeds and writes files outside the intended directory

If Langflow version is 1.2.0 to 1.8.1 and the /api/v2/files endpoint is accessible to authenticated users without proper boundary containment on the LocalStorageService, the environment is affected.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.9.0 or later
Fixed in 1.9.0
Interim mitigation

Upgrade to Langflow version 1.9.0 which contains the updated fix. If unable to upgrade immediately, restrict authenticated access to the file upload endpoint and implement network-level controls.

Recommended fix High confidence

1.9.0

  1. 1. Identify the current installed version of Langflow by running: pip show langflow or checking your requirements.txt
  2. 2. Upgrade Langflow to version 1.9.0 or later using: pip install langflow>=1.9.0 --upgrade
  3. 3. Verify the upgrade was successful by running: pip show langflow and confirming the version number
  4. 4. Restart the Langflow service to ensure the patched code is loaded into memory
  5. 5. If using a containerized deployment, rebuild and redeploy the container with the updated Langflow version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Langflow Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,448.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-33309 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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