---
id: "CVE-2026-55255"
kind: "vulnerability"
aliases: ["CVE-2026-55255"]
title: "Langflow is a tool for building and deploying AI-powered agents and workflows"
severity: "critical"
cvss: 8.4
epss: null
exploited: true
status: "open"
category: "ai-tooling"
products: [{"name": "Langflow Langflow", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "langflow", "fixed": ["1.9.1"], "affected": "< 1.9.1", "ecosystem": "pypi"}, {"name": "langflow", "fixed": ["1.9.1"], "affected": "< 1.9.1", "ecosystem": "vendor"}]
ecosystems: ["pypi", "vendor"]
tags: ["ai-agents", "ai-tooling", "exploited", "langflow", "poc-public", "self-hosted"]
not_affected_if: ["patched-1.9.1", "single-user-instance", "unauthenticated-only-deployment"]
published_at: "2026-06-23T17:17:08+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T23:44:51+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-55255", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-23T20:46:22+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55255", "first_seen_at": "2026-10-23T23:44:51+00:00"}]
---

# Langflow is a tool for building and deploying AI-powered agents and workflows

Langflow's /api/v1/responses endpoint looks up a flow by UUID without checking who owns it. Any authenticated user, including one with only an API key, can run another user's flow by passing the victim's flow ID as 'model'. That exposes the data the flow handles and the credentials and tools it can reach. It is exploited in the wild (CISA KEV, 2026-07-07).

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Langflow Langflow affected ? fixed ?
- pypi:langflow affected < 1.9.1 fixed 1.9.1
- vendor:langflow affected < 1.9.1 fixed 1.9.1

## How to check

Run 'pip show langflow' (or check the container image tag). Any version below 1.9.1 is vulnerable. Check logs for POST /api/v1/responses calls where the flow ID in 'model' belongs to a different user than the API key. Test: with a second user's API key, POST /api/v1/responses with model=<other user's flow ID>. A 200 means you are vulnerable; 404 means patched.

## Fix

Upgrade langflow to 1.9.1 or later (1.9.2+ is fine). Until then, restrict access to the API and don't give untrusted users accounts. Rotate API keys and any secrets used by flows on an exposed instance, and review flow executions since June 2026.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-55255
- 2026-10-23T20:46:22+00:00 analyst — Langflow's own advisory GHSA-qrpv-q767-xqq2 says affected < 1.9.1 and fixed in 1.9.1 (PR #12832). Some aggregators say 1.9.2; the vendor page says 1.9.1. The advisory rates it 9.9 Critical, and NVD rates it 8.4. The advisory includes a curl PoC. CISA KEV lists it as exploited; I did not read the Sysdig report myself, only a search summary of it, which says it was chained with CVE-2026-33017.
- 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-55255

## Documents

- [advisory] GHSA-qrpv-q767-xqq2 Langflow IDOR in /api/v1/responses https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
- [discussion] CSA note: Langflow authorization bypass added to KEV https://labs.cloudsecurityalliance.org/research/csa-research-note-langflow-idor-kev-cve-2026-55255-20260712/
- [fix] GHSA-qrpv-q767-xqq2 Langflow IDOR in /api/v1/responses https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2
- [poc] GHSA-qrpv-q767-xqq2 Langflow IDOR in /api/v1/responses https://github.com/langflow-ai/langflow/security/advisories/GHSA-qrpv-q767-xqq2

## From the sources

Langflow contains an authorization bypass through user-controlled key vulnerability which allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request.

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_