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CVE-2026-55581— mcp-shell: Secure Mode Allowlist Bypass via Default `/bin/bash` Executable

Quick assessment

Affected
sonirico mcp-shell
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

mcp-shell 是一个 MCP（Model Context Protocol）服务器，旨在以安全、可审计和按需的方式执行 shell 命令。在版本 0.6.0 之前，默认的 Docker 安全配置文件 security.yaml 将 列入 allowed_executables（允许执行的程序）列表中；同时，security.go 仅验证命令参数的第一个令牌（token），而 checkBlockedPatternsAndCommands 函数并未拒绝 shell 命令模式标志 。攻击者可以通过调用 shell

CVSS 8.4 · High

Affected Version Matrix 1

VendorProduct Version RangeStatus
sonirico mcp-shell < 0.6.0 affected
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I. Basic Information for CVE-2026-55581

Vulnerability Information
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Vulnerability Title
mcp-shell: Secure Mode Allowlist Bypass via Default `/bin/bash` Executable
Source: CVE Program / CVE List V5
Vulnerability Description
mcp-shell is an MCP server for running shell commands securely, auditably, and on demand. Prior to 0.6.0, the default Docker security.yaml includes /bin/bash in allowed_executables, while security.go validates only the first token and checkBlockedPatternsAndCommands does not reject the shell command-mode flag -c. A caller of the shell_exec MCP tool can provide the command argument `/bin/bash -c <arbitrary-command>`, which passes validation and reaches executor.go, where parseCommand and exec.CommandContext execute the arbitrary command as mcpuser outside the intended allowlist. This issue is fixed in version 0.6.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
OS命令中使用的特殊元素转义处理不恰当(OS命令注入)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
sonirico mcp-shell < 0.6.0 -

II. Public POCs for CVE-2026-55581

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 10219 chars
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III. Intelligence Information for CVE-2026-55581

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Patches & Fixes for CVE-2026-55581 (2)

Vendor Advisories for CVE-2026-55581 (1)

Vendor Pages for CVE-2026-55581 (1)

Same Patch Batch · sonirico · 2026-08-25 · 3 CVEs total

CVE-2026-55580 8.6 HIGH mcp-shell — Security Disabled by Default in Bare-Binary Deploy Path + Shell Interpreter in
CVE-2026-55582 8.4 HIGH mcp-shell: Secure Mode Allowlist Bypass via Git Shell Alias

IV. Related Vulnerabilities

Same product: mcp-shell
Same vendor: sonirico
Same weakness: CWE-78

V. Comments for CVE-2026-55581

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