OS command injection in mac-shell-mcp lets clients bypass command whitelist
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-78.
Summary
mac-shell-mcp from 0 before 2.0.0 by cfdude contains an OS command injection flaw, CWE-78. Shell metacharacters injected into execute_command arguments bypass the command whitelist. An MCP client, or a malicious prompt, can run forbidden commands as the server user without approval by pairing a safe command such as pwd with metacharacter arguments. The attack needs local access with low privileges.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
mac-shell-mcp before 2.0.0 contains an OS command injection vulnerability that allows MCP clients to bypass the command whitelist by injecting shell metacharacters into execute_command arguments. Attackers or malicious prompts can call a safe command such as pwd with arguments like ';' to run forbidden commands as the server user without approval.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Update cfdude mac-shell-mcp to version 2.0.0.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
- Fix · CNA mac-shell-mcp (cfdude) Fixed in 2.0.0
Timeline
- 2026-10-12 Threatist record created from CVE-2026-108953
- 2026-10-12 Alias added: GHSA-ffv7-8x5h-5w7r
- 2026-10-13 Priority changed: MEDIUM → LOW
- 2026-10-13 CISA SSVC decision points changed
- 2026-10-13 Priority changed: LOW → MEDIUM
References
Sources
- CVE-2026-108953 · CVE Program
- CVE-2026-108953 · NVD
- FIRST EPSS
- GHSA-ffv7-8x5h-5w7r · GitHub Advisory Database · CC BY 4.0
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