mac-shell-mcp OS command injection via shell metacharacters

mac-shell-mcp before version 2.0.0 contains an OS command injection vulnerability allowing MCP clients to bypass command whitelist restrictions by injecting shell metacharacters into execute_command arguments, enabling execution of forbidden commands.

Disclosed 12 October 2026 · Record updated 12 October 2026

Impact

MCP clients can bypass command whitelist protections and execute arbitrary commands as the server user without approval through shell metacharacter injection.

Our coverage

A guard stands before a locked gate holding a list of approved visitors, but a cloaked figure slips through by hiding behind a punctuation mark the guard failed to notice.

Vulnerabilities

Command whitelist in mac-shell-mcp bypassed with a semicolon

CVE-2026-108953 lets MCP clients slip shell metacharacters into arguments and run commands the server was meant to block.

12 Oct 2026

Sources

nvd.nist.govhttps://nvd.nist.gov/vuln/detail/CVE-2026-108953