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CVE-2026-55580

mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in Secure-Mode Allowlist

HIGH
8.6
CVSS Score
Published: August 25, 2026 at 03:42 PM UTC
Updated: September 9, 2026 at 09:27 PM UTC
1 product affected across 1 vendorMcp Shell

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Severity
HIGH8.6
Exploit prediction
EPSS 0.2%
SSVC
PoC

Description

mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, config.go initializes Security.Enabled to false, and when MCP_SHELL_SEC_CONFIG_FILE is unset, main.go starts the documented bare-binary deployment without a security policy. SecurityValidator.validateCommand in security.go then short-circuits and allows every command supplied to the shell_exec MCP tool, so an LLM connected over stdio can execute unrestricted OS commands as the mcp-shell process user. The README from-source installation and MCP client configuration omit MCP_SHELL_SEC_CONFIG_FILE, making the insecure state the documented default. This issue is fixed in version 0.6.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mcp Shell· Sonirico
60%
v < 0.6.0
Affected range stops below 0.6.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (4)

x_refsource_CONFIRM
Source: cverecord
https://github.com/sonirico/mcp-shell/security/advisories/GHSA-f5pj-2738-996m
x_refsource_MISC
Source: cverecord
https://github.com/sonirico/mcp-shell/pull/16
x_refsource_MISC
Source: cverecord
https://github.com/sonirico/mcp-shell/commit/f31377fce6ec31114e5a4398c0e5270552bce09f
x_refsource_MISC
Source: cverecord
https://github.com/sonirico/mcp-shell/releases/tag/v0.6.0

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.6HIGHGitHub_M
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-78

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