Langflow has Unauthenticated Remote Code Execution via Public Flow Build Endpoint
Affects Langflow before 1.9.0 on instances with at least one public flow. No vendor rating is given beyond the CVSS score of 9.3. Fixed in 1.9.0.
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 1.9.0
- 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
Summary
Langflow, a tool for building and deploying AI-powered agents and workflows, is affected. An unauthenticated attacker can run arbitrary code on the server through a public flow build endpoint, which could give them full control over the affected system.
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. In versions prior to 1.9.0, the POST /api/v1/build_public_tmp/{flow_id}/flow endpoint allows building public flows without requiring authentication. When the optional data parameter is supplied, the endpoint uses attacker-controlled flow data (containing arbitrary Python code in node definitions) instead of the stored flow data from the database. This code is passed to exec() with zero sandboxing, resulting in unauthenticated remote code execution. This is distinct from CVE-2025-3248, which fixed /api/v1/validate/code by adding authentication. The build_public_tmp endpoint is designed to be unauthenticated (for public flows) but incorrectly accepts attacker-supplied flow data containing arbitrary executable code. This issue has been fixed in version 1.9.0.
Timeline
- CVE published
- Added to CISA KEV
CISA has evidence of exploitation in the wild
- CISA remediation deadline
Due date for US federal agencies to patch
- Record last updated
- EPSS reached 10%
FIRST estimates at least a 10% chance of exploitation in the next 30 days
Affected versions
- langflow-ai langflow
fixed in 1.9.0
- langflowPyPI
fixed in 1.9.0
References 3
GitHub · langflow-ai/langflow
GitHub Advisory Database
Questions about CVE-2026-33017
What does this mean?
The flaw lets an unauthenticated remote party run code on the Langflow server through the public flow build endpoint, with the full privileges of the server process. The attacker must know the UUID of a public flow.Source: github.com
Am I affected, and how do I check?
Langflow versions before 1.9.0 are affected, but only on instances that have at least one public flow. To check, look at the installed Langflow version and whether any flow on the instance is public.Source: github.com
What should I do about it?
Upgrade Langflow to version 1.9.0 or later, which is the fixed release listed for this vulnerability.Source: github.com
Is it being exploited?
Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-03-25, which means it has evidence of attacks. No public exploit code is tracked.Source: cisa.gov, cve.now feed data