CVE-2026-40933: CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in FlowiseAI Flowise
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.
AI Analysis
Technical Summary
CVE-2026-40933 is an OS command injection vulnerability in FlowiseAI's Flowise product before version 3.1.0. The flaw arises from unsafe serialization of stdio commands in the MCP adapter, allowing authenticated users to add a Custom MCP with arbitrary commands. Input sanitization mechanisms such as validateCommandInjection and validateArgsForLocalFileAccess are bypassed by combining allowed commands with malicious arguments, enabling execution of arbitrary OS commands. This vulnerability is resolved in Flowise version 3.1.0.
Potential Impact
Successful exploitation allows an authenticated attacker to execute arbitrary operating system commands on the host running Flowise, leading to full compromise of confidentiality, integrity, and availability of the system. The CVSS 3.1 base score of 10.0 reflects the critical impact with network attack vector, low attack complexity, and no user interaction required beyond authentication.
Mitigation Recommendations
Upgrade Flowise to version 3.1.0 or later, where this vulnerability is fixed. Since the vulnerability is resolved in the official release, applying this update fully mitigates the risk. No other vendor advisories or temporary fixes are indicated. Patch status is confirmed by the vendor's versioning information.
CVE-2026-40933: CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in FlowiseAI Flowise
Description
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-40933 is an OS command injection vulnerability in FlowiseAI's Flowise product before version 3.1.0. The flaw arises from unsafe serialization of stdio commands in the MCP adapter, allowing authenticated users to add a Custom MCP with arbitrary commands. Input sanitization mechanisms such as validateCommandInjection and validateArgsForLocalFileAccess are bypassed by combining allowed commands with malicious arguments, enabling execution of arbitrary OS commands. This vulnerability is resolved in Flowise version 3.1.0.
Potential Impact
Successful exploitation allows an authenticated attacker to execute arbitrary operating system commands on the host running Flowise, leading to full compromise of confidentiality, integrity, and availability of the system. The CVSS 3.1 base score of 10.0 reflects the critical impact with network attack vector, low attack complexity, and no user interaction required beyond authentication.
Mitigation Recommendations
Upgrade Flowise to version 3.1.0 or later, where this vulnerability is fixed. Since the vulnerability is resolved in the official release, applying this update fully mitigates the risk. No other vendor advisories or temporary fixes are indicated. Patch status is confirmed by the vendor's versioning information.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-15T20:40:15.518Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69e7e91619fe3cd2cdfaec46
Added to database: 4/21/2026, 9:16:06 PM
Last enriched: 4/21/2026, 9:31:07 PM
Last updated: 4/22/2026, 6:03:20 AM
Views: 13
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