---
title: "CVE-2026-55157: Token Optimizer MCP - Command Injection"
description: "Token Optimizer MCP < 5.1.0 contains a command injection caused by improper sanitization of the username argument in the smart_user tool's get-user-info operation, letting attackers execute arbitrary OS commands with server user privileges, exploit requires access to MCP client calling smart_user."
url: https://panop.io/threat-heartbeat/CVE-2026-55157/
---

# CVE-2026-55157 Token Optimizer MCP - Command Injection

Token Optimizer MCP < 5.1.0 contains a command injection caused by improper sanitization of the username argument in the smart\_user tool's get-user-info operation, letting attackers execute arbitrary OS commands with server user privileges, exploit requires access to MCP client calling smart\_user.

CVSS base score 8.4 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.70% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-55157)

## Details

Type

Command Injection

Impact

Remote Code Execution

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Published

28 September 2026

Updated

15 October 2026

Weakness

[CWE-78](https://cwe.mitre.org/data/definitions/78.html)

## Vendor fix

Upgrade to version 5.1.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-55157](https://nvd.nist.gov/vuln/detail/CVE-2026-55157)
- [https://github.com/ooples/token-optimizer-mcp/commit/b4ee96dac799cbfba0a9f9c17844ce9d613cbcc7](https://github.com/ooples/token-optimizer-mcp/commit/b4ee96dac799cbfba0a9f9c17844ce9d613cbcc7)
- [https://github.com/ooples/token-optimizer-mcp/releases/tag/v5.1.0](https://github.com/ooples/token-optimizer-mcp/releases/tag/v5.1.0)
- [https://github.com/ooples/token-optimizer-mcp/security/advisories/GHSA-49mq-fc6q-3h46](https://github.com/ooples/token-optimizer-mcp/security/advisories/GHSA-49mq-fc6q-3h46)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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