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PatchSiren cyber security CVE debrief

CVE-2026-108953 cfdude CVE debrief

The mac-shell-mcp package before version 2.0.0 contains an OS command injection vulnerability. This vulnerability allows MCP clients to bypass the command whitelist by injecting shell metacharacters into execute_command arguments, potentially leading to unauthorized command execution as the server user. Defenders should assess exposure and prioritize verification and remediation efforts. The CVE record was published on 2026-10-12T12:13:05.422Z and has not been modified since then. The vulnerability has a high CVSS score of 8.5, indicating a significant risk to affected deployments.

Vendor
cfdude
Product
mac-shell-mcp
CVSS
HIGH 8.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-12
Original CVE updated
2026-10-12
Advisory published
2026-10-12
Advisory updated
2026-10-12

Who should care

Defenders responsible for mac-shell-mcp deployments should assess exposure and prioritize verification and remediation efforts. This includes operators, platform administrators, vulnerability management teams, and security teams who need to ensure that affected systems are upgraded to version 2.0.0 or later and that compensating controls are in place for exposed systems.

Why it matters

Defenders should prioritize verifying and upgrading to version 2.0.0 or later of mac-shell-mcp, assessing exposure in their environments, and monitoring for potential exploitation attempts due to the high CVSS score of 8.5 and the potential for unauthorized command execution.

  • Potential unauthorized command execution as the server user
  • Bypassing of command whitelist
  • Injection of shell metacharacters into execute_command arguments
  • Possible lateral movement and exploitation

Technical summary

The mac-shell-mcp package before version 2.0.0 contains an OS command injection vulnerability. This vulnerability allows MCP clients to bypass the command whitelist by injecting shell metacharacters into execute_command arguments, potentially leading to unauthorized command execution as the server user. The vulnerability is due to insufficient input validation and sanitization of user-supplied input. Attackers can exploit this vulnerability by sending crafted requests to the affected system, potentially leading to unauthorized command execution.

Defensive priority

Defenders should prioritize verifying and upgrading to version 2.0.0 or later of mac-shell-mcp, assessing exposure in their environments, and monitoring for potential exploitation attempts.

Recommended defensive actions

  • Verify and upgrade to version 2.0.0 or later of mac-shell-mcp
  • Assess exposure in environments using mac-shell-mcp
  • Monitor for potential exploitation attempts
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the OS command injection vulnerability in mac-shell-mcp before 2.0.0, allowing MCP clients to bypass the command whitelist by injecting shell metacharacters into execute_command arguments.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-108953 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-108953

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-108953 NVD vulnerability detail

    Publisher, destination, and source semantics verified

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

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • mac-shell-mcp before 2.0.0 OS Command Injection via execute_command Arguments

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/108xxx/CVE-2026-108953.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://github.com/cfdude/mac-shell-mcp/issues/45

    Supplemental source - issue-tracking

  • Source reference

    Unverified legacy reference

    URL: https://github.com/cfdude/mac-shell-mcp/commit/932ce733cde07bb30b1f186303e6692dbb5d087a

    Supplemental source - patch

  • Source reference

    Unverified legacy reference

    URL: https://github.com/cfdude/mac-shell-mcp/blob/1c1708201abb7a18c83075e1bf933e7a92cbeb9f/src/services/command-service.ts

    Supplemental source - technical-description

  • Source reference

    Unverified legacy reference

    URL: https://github.com/cfdude/mac-shell-mcp

    Supplemental source - product

  • Source reference

    Unverified legacy reference

    URL: https://www.vulncheck.com/advisories/mac-shell-mcp-before-2.0.0-os-command-injection-via-execute-command-arguments

    Supplemental source - third-party-advisory

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.