CVE-2026-56274: Flowiseai Flowise

Critical severity, CVSS 9.9. EPSS: 7.5% chance of exploitation in the next 30 days.

Flowise before 3.1.2 contains multiple OS command injection vulnerabilities in the Custom MCP Server feature due to incomplete command-flag validation and a regex bypass in local file access restrictions. An attacker with a Flowise account of any role, or API access with view/update permissions for chatflows, can configure a malicious MCP server to bypass the validateCommandFlags blocklist (for example, 'docker build' is not blocked, and 'npx --yes' is not blocked while only '-y' is) and the validateArgsForLocalFileAccess checks, resulting in execution of arbitrary commands on the Flowise host.

Affected products

• Flowiseai Flowise: before 3.1.2 (fixed in 3.1.2)

Published 2026-06-23. Last modified 2026-06-25.