CVE-2026-33017
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedLangflow 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe Langflow build_public_tmp endpoint accepts optional attacker-controlled flow data containing arbitrary Python code in node definitions, which gets passed to exec() with zero sandboxing. Since this endpoint is intentionally designed to be unauthenticated for public flows, any unauthenticated attacker can achieve remote code execution by supplying malicious flow data.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 1.8.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm Langflow is installedRun 'pip show langflow' or check for langflow process running (ps aux | grep langflow)Affected if Langflow is installed and running
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Check installed Langflow versionRun 'pip show langflow' and note the Version field, or check the running service's version endpoint if availableAffected if Version is less than 1.8.2 (vulnerable) or cannot be determined (treat as vulnerable)
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Verify vulnerable endpoint existsCheck if the API endpoint /api/v1/build_public_tmp/{flow_id}/flow is available by reviewing the Langflow source code or routing configuration in the installation directoryAffected if Endpoint exists in the codebase (pre-1.8.2 versions contain this endpoint)
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Check network exposure of APIReview firewall rules, reverse proxy configuration, or Kubernetes/network policies to determine if the Langflow API port (default 7860) is exposed to untrusted networks or the internetAffected if API port is accessible from untrusted networks without authentication controls
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Inspect access logs for exploitation attemptsCheck Langflow access logs for POST requests to /api/v1/build_public_tmp/*/flow with unusual data payloads, or look for exec() errors in application logsAffected if Suspicious requests found or evidence of successful exploitation in logs
You are affected if Langflow is running with version < 1.8.2 AND the API is accessible to untrusted users, as the vulnerable endpoint requires no authentication and executes arbitrary Python code from the request body.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.8.2
Upgrade to Langflow version 1.9.0 or later. If immediate patching is not feasible, restrict or disable access to the /api/v1/build_public_tmp/{flow_id}/flow endpoint at the network level until the upgrade can be completed.
Langflow 1.9.0 or later
- Upgrade Langflow to version 1.9.0 or later to resolve the code injection vulnerability
- If using pip, run: pip install langflow==1.9.0 or pip install langflow>=1.9.0
- If using Docker, update your image to use the 1.9.0 tag or later: docker pull langflowai/langflow:1.9.0
- After upgrade, verify the /api/v1/build_public_tmp/{flow_id}/flow endpoint no longer accepts attacker-supplied Python code in the data parameter
- Confirm the upgrade by checking the Langflow version (e.g., via API or admin interface)
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-33017 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-33017 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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