Flowise disclosed a critical remote code execution flaw, tracked as CVE-2026-56274, affecting versions before 3.1.2 in the Custom MCP Server feature. The vulnerability stems from multiple OS command injection paths in validateCommandFlags and validateArgsForLocalFileAccess, allowing attackers to configure a malicious MCP server and execute arbitrary commands on the Flowise host. The issue is rated CVSS 9.9 and is remotely exploitable.
Advisories describe three bypass techniques: an incomplete Docker argument blocklist that permits docker build with a remote URL, an npx blocklist bypass where --yes is allowed even though -y is blocked, and a Unix path validation weakness that lets paths beginning with // evade local file access checks for node. Exploitation requires any Flowise account role or API access with view and update permissions for chatflows. Organizations were urged to upgrade to Flowise 3.1.2 or later, review MCP server configurations, and restrict chatflow management permissions.

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4 events from the most recent confirmed update back to the earliest known activity.
A Rapid7 Metasploit pull request added the module `exploit/multi/http/flowise_mcp_rce` targeting CVE-2026-56274 in Flowise's MCP Server. The reference includes accompanying documentation and a demonstration showing successful remote command execution on a target system.
CVE-2026-56274 was published describing a critical remote code execution vulnerability in Flowise before version 3.1.2 caused by MCP security bypasses. The entry notes a CVSS 3.1 score of 9.9 and recommends upgrading to Flowise 3.1.2 or later.
A GitHub security advisory disclosed three bypass techniques in Flowise's Custom MCP Server feature that can lead to arbitrary command execution on the Flowise server. The advisory states the issues affect vulnerable code in validateCommandFlags and validateArgsForLocalFileAccess and require a Flowise account or API access with chatflow view/update permissions.
A GitHub security advisory disclosed that Flowise versions up to and including 2.2.7-patch.1 allow unsandboxed remote command execution through the Custom MCP feature via the /api/v1/node-load-method/customMCP endpoint. The advisory said default unauthenticated deployments increase exposure and included proof-of-concept details showing arbitrary command execution and potential full server or container compromise.
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