What is CVE-2026-55157?

CVE-2026-55157 is a high-severity vulnerability, classified under OS Command Injection. CVSS score: 8.4/10. Published 2026-09-28.

How severe is CVE-2026-55157?

High severity. CVSS v3 base score is 8.4 out of 10.

CVE-2026-55157

CVE-2026-55157

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.

Vulnerability class: Command Injection (OS Command Injection)

Published 2026-09-28.

CVSS v3 metric

CVSS v3 base score 8.4 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

Frequently asked questions

What is CVE-2026-55157?: CVE-2026-55157 is a high-severity vulnerability, classified under OS Command Injection. CVSS score: 8.4/10. Published 2026-09-28.
How severe is CVE-2026-55157?: High severity. CVSS v3 base score is 8.4 out of 10.