xszyou Fay 4.3.1 MCP STDIO Server Management os command injection

Summaryinfo

A vulnerability categorized as very critical has been discovered in xszyou Fay 4.3.1. This affects an unknown part of the component MCP STDIO Server Management. Such manipulation leads to os command injection. This vulnerability is documented as CVE-2026-30618. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in xszyou Fay 4.3.1 and classified as very critical. Affected by this issue is an unknown functionality of the component MCP STDIO Server Management. The manipulation with an unknown input leads to a os command injection vulnerability. Using CWE to declare the problem leads to CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. CVE summarizes:

xszyou Fay 4.3.1 contains a remote code execution vulnerability in its MCP STDIO server management and command execution handling. A remote attacker can access the publicly exposed MCP management interface and configure an MCP STDIO server with attacker-controlled commands and parameters, resulting in execution of arbitrary commands on the server. Successful exploitation allows arbitrary command execution within the context of the Fay service.

The advisory is shared for download at ox.security. This vulnerability is handled as CVE-2026-30618 since 03/04/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/16/2026). The MITRE ATT&CK project declares the attack technique as T1202.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• xszyou

Name

• Fay

Version

• 4.3.1

CPE 2.3info

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CPE 2.2info

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