RCE in Flowise
CVE-2026-56274
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.
Vulnerability class: Command Injection (OS Command Injection)
EPSS: 0.075 (94.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Flowise — versions 0, 3.1.2
- Flowise Components — versions 0, 3.1.2
- Flowiseai Flowise
Weakness classification (CWE)
Public proof-of-concept exploits
References
- disclosure@vulncheck.com (Exploit, vendor-advisory, Third Party Advisory)
- disclosure@vulncheck.com (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-56274?
- CVE-2026-56274 is a critical-severity vulnerability in Flowise, classified under OS Command Injection. CVSS score: 9.9/10. Published 2026-06-23.
- How severe is CVE-2026-56274?
- Critical severity. CVSS v3 base score is 9.9 out of 10.
- Is CVE-2026-56274 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.