CVE-2026-30618Network attack vector

Unauthenticated command execution via MCP STDIO configuration

Published Jul 15, 2026 · Updated Jul 15, 2026

Command injection in xszyou Fay 4.3.1 allows remote attackers to execute arbitrary commands through the exposed MCP Web-GUI. The MCP adapter in faymcp/mcp_client.py passes attacker-controlled command and argument values to StdioServerParameters without sanitization or an approved allowlist, causing the underlying system to launch them as a subprocess. Unauthenticated network access to the Web-GUI is sufficient, and commands run with the privileges of the Fay process.

CVSS severity9.8
Critical
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in xszyou Fay 4.3.1 allows remote attackers to execute arbitrary commands through the exposed MCP Web-GUI. The MCP adapter in faymcp/mcp_client.py passes attacker-controlled command and argument values to StdioServerParameters without sanitization or an approved allowlist, causing the underlying system to launch them as a subprocess. Unauthenticated network access to the Web-GUI is sufficient, and commands run with the privileges of the Fay process.

The record

CVE
CVE-2026-30618
Published
Jul 15, 2026
Updated
Jul 15, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-94, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-94Improper Control of Generation of Code ('Code Injection')
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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