Langflow: IDOR Vulnerability in `/api/v1/responses` Endpoint Allows Authenticated Attackers to Access Another User's Flow
Affects Langflow before 1.9.1 for authenticated users who know another user's flow ID. CVSS scores it 8.4 (high). Fixed in 1.9.1.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Actively exploited
- Fix
- Fixed in 1.9.1, 1.9.2
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: active
- Automatable: no
- Technical impact: total
Summary
Langflow, a tool for building and deploying AI-powered agents and workflows, is affected. An authenticated attacker can exploit a flaw in its responses API endpoint to run another user's flow by supplying that user's flow ID, bypassing access controls meant to keep flows private.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original 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.
Timeline
- CVE published
- Added to CISA KEV
CISA has evidence of exploitation in the wild
- CISA SSVC assessment
Exploitation: active · Automatable: no · Technical impact: total
- CISA remediation deadline
Due date for US federal agencies to patch
- Record last updated
Affected versions
- langflow-ai langflow
fixed in 1.9.1
- langflowPyPI
fixed in 1.9.1
- langflowPyPI
fixed in 1.9.2
References 3
GitHub · langflow-ai/langflow
Questions about CVE-2026-55255
What does this mean?
A logged-in Langflow user can run another user's flow by supplying that flow's ID in a request to the /api/v1/responses endpoint. The flow then executes with the victim's resources and can expose data the victim's flows process.Source: github.com
Am I affected, and how do I check?
Langflow versions before 1.9.1 of the langflow pip package are affected. To check, look at the installed version (for example with pip show langflow); the attacker must also know the victim's flow ID (UUID).Source: github.com
What should I do about it?
Upgrade the langflow pip package to 1.9.1 or later, which contains the fix.Source: github.com
Is it being exploited?
Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-07-07, which means it has evidence of attacks. No public exploit code is tracked.Source: cisa.gov, cve.now feed data