Langflow: Unauthenticated Flow Execution via Webhook Authentication Bypass

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-8505: 0.87% estimated exploitation activity in the next 30 days; percentile 58.87 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A vulnerability in Langflow's webhook authentication logic allows unauthenticated users to trigger the execution of any flow. The system incorrectly bypasses API key validation when the WEBHOOKAUTHENABLE configuration is set to False. This allows a remote attacker who knows a flow's UUID to execute it as if they were the owner, potentially leading to Remote Code Execution (RCE) or Denial of Service (DoS). Details The WEBHOOKAUTHENABLE setting was introduced in v1.7.0 (#9139) with a default of False. The root cause is in the webhook authentication path, AuthService.getwebhookuser (src/backend/base/langflow/services/auth/service.py; the thin wrapper in src/backend/base/langflow/services/auth/utils.py just delegates to it): By default (v1.7.0 through v1.9.0), Langflow treats WEBHOOKAUTHENABLE as False, meaning all webhook endpoints are public. This relies exclusively on the secrecy of the flowid (UUID), which is an insecure practice (Security by Obscurity). A related report,…

Published by the source

5 Oct 2026, 22:31 UTC

Last modified by the source

15 Oct 2026, 14:56 UTC

Source last checked

26 Oct 2026, 13:55 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cf6m-vc3m-7cgm

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-cf6m-vc3m-7cgm

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-cf6m-vc3m-7cgm

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# Patch Next advisory brief: CVE-2026-8505

Advisory: Langflow: Unauthenticated Flow Execution via Webhook Authentication Bypass
IDs: CVE-2026-8505, GHSA-cf6m-vc3m-7cgm
Record: https://patchnext.com/advisories/cve-2026-8505 (revision 3, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: langflow 1.9.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI langflow: affected >= 1.7.0, <= 1.9.0; fixed in 1.9.1

## Suggested inspection (read-only)
- `python -m pip show langflow`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on langflow.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cf6m-vc3m-7cgm (GitHub-reviewed advisory GHSA-cf6m-vc3m-7cgm lists affected ranges: PyPI langflow >=1.7.0 <=1.9.0)
- Verified: https://osv.dev/vulnerability/GHSA-cf6m-vc3m-7cgm (OSV record GHSA-cf6m-vc3m-7cgm lists affected ranges: PyPI langflow >=1.7.0 <1.9.1 (fixed))

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