Command Allowlist Bypass in cli-mcp-server by MladenSU
CVE-2026-85660

9.2CRITICAL

Key Information:

Vendor

Mladensu

Status
Cli-mcp-server
Vendor
CVE Published:
4 September 2026

What is CVE-2026-85660?

The flaw in version 0.2.5 of cli-mcp-server arises from a command allowlist bypass in the _validate_command_with_operators function. When the ALLOW_SHELL_OPERATORS feature is enabled, unauthorized attackers can exploit shell command substitution techniques such as $(...) and backticks, allowing them to execute commands that are not part of the ALLOWED_COMMANDS validation check. This could potentially lead to unauthorized command execution, raising significant security concerns.

Affected Version(s)

cli-mcp-server 0 <= 0.2.5

References

https://github.com/MladenSU/cli-mcp-server/issues/17
issue-tracking
https://github.com/MladenSU/cli-mcp-server
product
https://github.com/MladenSU/cli-mcp-server/blob/main/src/...
technical-description

CVSS V4

Score:
9.2
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

George Chen
.