Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access…
Langflow
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- Severity
- High, CVSS 8.4
- CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
- Record
- CVE-2026-55255
- Affects
- Langflow
- Known exploited
- Yes, listed in the CISA Known Exploited Vulnerabilities catalog
- Published
- Record first published by the source
- June 23, 2026
- Source last modified
- October 25, 2026
Description
Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, an Insecure Direct Object Reference (IDOR) vulnerability in /api/v1/responses endpoint allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request. This vulnerability is fixed in 1.9.1.
Description quoted from the NVD record.
Who is affected
Your organization is affected if it uses Langflow, a tool for building and running apps and automated workflows that use AI language models. This flaw affects all versions before 1.9.1. Someone who already has an account on your Langflow installation could use a part of the product that runs workflows on request to run any workflow that belongs to another user, simply by giving that workflow's identifier. This flaw is rated High. It is on CISA's Known Exploited Vulnerabilities list, which means attacks using it have been seen.
What to do
- If you or someone on your staff installed and runs Langflow, have that person update it to version
1.9.1or later as soon as possible. - If an IT provider or vendor runs Langflow for your organization, send them this advisory and ask when the update will be done.
- Because attacks using this flaw have been seen, treat this update as urgent rather than waiting for a regular maintenance window.
- If you are not sure whether your organization uses Langflow, ask whoever looks after your computers and online services to check.
Analysis written from the source record as of October 25, 2026 and reviewed before publishing.