CVE-2026-55255
Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow
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.
In plain language
AI Worth attentionIn Langflow, an authenticated attacker can use another user’s flow ID to run that other flow via the /api/v1/responses endpoint—this is serious if you have untrusted users who can log in, and you should upgrade to 1.9.2.
CVE-2026-55255 is an IDOR in Langflow’s /api/v1/responses endpoint that lets authenticated attackers access and execute another user’s flow by supplying the victim’s flow ID in their request; fixed in langflow 1.9.2.
What to do now
- Check your Langflow version and confirm whether you are running a version older than 1.9.2.
- If you are older than 1.9.2, plan an upgrade to Langflow 1.9.2 as soon as possible.
- Review who has accounts that can access Langflow and treat any “guest” or contractor accounts as untrusted unless needed.
- After upgrading, verify that requests to /api/v1/responses only allow access to flows owned by the logged-in user.
CVSS Vector Breakdown
AV:NAttack VectorAC:HAttack ComplexityPR:LPrivileges RequiredUI:NUser InteractionS:CScopeC:HConfidentialityI:HIntegrityA:LAvailabilityWeaknesses
Affected Products
Exploitability
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.
Attack Graph
Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.
MITRE ATT&CK
1 techniqueReferences
- CISA orders urgent action on actively exploited Langflow RCE flawen-us·BleepingComputer· Exploited Langflow ai-ml
- New ENCFORGE Ransomware Targets AI Model Files in Langflow RCE Attacken·The Hacker News· Exploited Langflow JADEPUFFER
- Week in review: Accenture data breach, great open-source cybersecurity toolsen-us·Help Net Security· Roundup
- Attackers using Langflow flaw for credential harvesting (CVE-2026-55255)en-us·Help Net Security· Exploited Langflow web-app
- CISA Urges Immediate Patching of Exploited ColdFusion, Langflow, Joomla Flawsen-us·SecurityWeek· Exploited Adobe ColdFusion web-app
- CISA orders feds to prioritize patching Langflow auth bypass flawen-us·BleepingComputer· Exploited Langflow ai-ml
- CISA Adds 4 Actively Exploited Adobe, Joomla, and Langflow Flaws to KEVen·The Hacker News· Exploited Adobe ColdFusion web-app
- 29th June – Threat Intelligence Reporten-us·Check Point Research·
- Langflow Security Vulnerabilities Expose AI Systemsen-us·Daily CyberSecurity (securityonline.info)· Patch langflow ai-ml
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