GHSA-c9gw-hvqq-f33r · Severity: critical · Ecosystem: npm — Flowise: Authenticated RCE Via MCP Adapters
Flowise is a drag & drop user interface to build a customized large language model flow. Prior to 3.1.0, due to unsafe serialization of stdio commands in the MCP adapter, an authenticated attacker can add an MCP stdio server with an arbitrary command, achieving command execution. The vulnerability lies in a bug in the input sanitization from the “Custom MCP” configuration in http://localhost:3000/canvas - where any user can add a new MCP, when doing so - adding a new MCP using stdio, the user can add any command, even though your code have input sanitization checks such as validateCommandInjection and validateArgsForLocalFileAccess, and a list of predefined specific safe commands - these commands, for example "npx" can be combined with code execution arguments ("-c touch /tmp/pwn") that enable direct code execution on the underlying OS. This vulnerability is fixed in 3.1.0.
Conclusion & alert: CVE-2026-40933 is rated High Exploit Risk (61.6/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.06%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
| EDB-ID | Source | Kind | Published | Link |
|---|---|---|---|---|
| — | nvd_ref | exploit_tag | Exploit-DB ↗ |
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-05-13 | 0.05% | 0.06% | +0.02% |
| 2 | 2026-04-28 | 0.07% | 0.05% | -0.02% |
| 3 | 2026-04-22 | — | 0.07% | — |
Full EPSS history (3 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 9.9 | 3.1 | CRITICAL |
|
3.1 | 6.0 | [email protected] |
GHSA-c9gw-hvqq-f33r · Severity: critical · Ecosystem: npm — Flowise: Authenticated RCE Via MCP Adapters
| URL | Tags |
|---|---|
| https://github.com/FlowiseAI/Flowise/security/advisories/GHSA-c9gw-hvqq-f33r | Exploit Vendor Advisory |
| https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem | Press/Media Coverage Third Party Advisory |
| https://www.ox.security/blog/the-mother-of-all-ai-supply-chains-critical-systemic-vulnerability-at-the-core-of-the-mcp | Press/Media Coverage Third Party Advisory |