Langflow Authorization Bypass Through User-Controlled Key Vulnerability
Langflow contains an authorization bypass through user-controlled key vulnerability which allows an authenticated attacker to execute any flow belonging to another user by specifying the victim's flow ID in the request.
Quick answer
Langflow should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Review vendor advisory for affected versions.
Fixed versions
- Apply the latest vendor-supported patched version.
How to fix it
Langflow is affected by an authorization bypass that can let an authenticated attacker execute another user's flow by supplying that flow ID. Upgrade to the fixed Langflow release from the GitHub advisory, restrict access, and review flow execution history. Because flows may contain model provider keys and sensitive integrations, rotate secrets if unauthorized access is suspected.
- Inventory every Langflow deployment, including production, internal tools, developer sandboxes, and public demos.
- Upgrade Langflow to the fixed release referenced in the GHSA advisory for CVE-2026-55255.
- Restrict Langflow access behind SSO, VPN, trusted reverse proxy rules, and least-privilege user roles.
- Review flow ownership, shared flows, API routes, workspace permissions, and authentication configuration for unsafe access patterns.
- Inspect flow execution logs, API access logs, and outbound calls for attempts to run other users' flows.
- Rotate model provider keys, Langflow API keys, database credentials, webhook secrets, and integration tokens if unauthorized flow execution is found.
- Rebuild and redeploy from trusted images after upgrading and clearing cached sessions.
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Verify the fix
- Confirm the running Langflow version is fixed for CVE-2026-55255.
- Validate users cannot execute flows they do not own by changing flow IDs in requests.
- Review logs for unauthorized flow execution or unusual model provider activity.
- Run regression tests for legitimate shared-flow and workspace workflows after the update.
- Run a Fixnx scan and confirm no public Langflow admin or API exposure remains.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-55255?
Langflow should be checked against the vendor advisory and trusted references linked on this page.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
Why can this risk appear in multiple categories?
A vulnerability can belong to more than one platform or ecosystem. Fixnx keeps one canonical risk page while also listing it in every relevant category.