CVE-2026-85660: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') in MladenSU cli-mcp-server
Description
cli-mcp-server 0.2.5 contains a command allowlist bypass vulnerability in the _validate_command_with_operators function when ALLOW_SHELL_OPERATORS is enabled. Attackers can use shell command substitution syntax like $(...) or backticks to execute non-allowlisted commands that bypass the ALLOWED_COMMANDS validation check.
CVSS v4.0
Score 9.2critical
Affected software
MladenSU
cli-mcp-server
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in cli-mcp-server 0.2.5 involves improper neutralization of special elements used in OS commands, specifically a command allowlist bypass in the _validate_command_with_operators function when the ALLOW_SHELL_OPERATORS feature is enabled. This allows attackers to use shell command substitution syntax (e.g., $(...) or backticks) to execute arbitrary commands that are not on the allowed commands list, effectively bypassing the intended command validation mechanism.
Potential Impact
Successful exploitation can lead to execution of arbitrary OS commands with the privileges of the cli-mcp-server process. This can result in unauthorized system access, data compromise, or system disruption. The CVSS 4.0 base score is 9.2 (critical), reflecting network attack vector, high complexity, no privileges required, no user interaction, and high impacts on confidentiality, integrity, and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, it is recommended to disable ALLOW_SHELL_OPERATORS if possible to prevent exploitation of the command allowlist bypass. Monitor vendor channels for updates and apply patches promptly once released.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-04T13:32:27.594Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a9adb43acd9273b49bef54b
Added to database: 09/04/2026, 14:52:51 UTC
Last enriched: 09/07/2026, 12:02:45 UTC
Last updated: 10/18/2026, 06:48:20 UTC
Views: 50
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