Token Optimizer MCP: OS command injection in smart_user via username in get-user-info

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-55157: 0.88% estimated exploitation activity in the next 30 days; percentile 59.17 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary token-optimizer-mcp is vulnerable to OS command injection in the smartuser tool. The get-user-info operation accepts a user-controlled username argument and later interpolates it into a shell command executed through execAsync(): Although the value is wrapped in double quotes, POSIX shells still evaluate command substitution such as $(...) and backticks inside double quotes. As a result, an MCP client can provide a crafted username such as: and execute arbitrary local commands with the privileges of the user running the MCP server. This is a CWE-78 OS command injection issue. Tested version: This issue is not related to the current npm audit dependency advisories. The vulnerability is in token-optimizer-mcp's own tool implementation. --- Details The vulnerable code path is in the smartuser implementation. The username argument is eventually passed into a shell command similar to: The problem is that username is controlled by the MCP tool caller and is inserted into a command…

Published by the source

14 Aug 2026, 21:42 UTC

Last modified by the source

14 Aug 2026, 21:42 UTC

Source last checked

26 Oct 2026, 13:01 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-49mq-fc6q-3h46

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# Patch Next advisory brief: CVE-2026-55157

Advisory: Token Optimizer MCP: OS command injection in smart_user via username in get-user-info
IDs: CVE-2026-55157, GHSA-49mq-fc6q-3h46
Record: https://patchnext.com/advisories/cve-2026-55157 (revision 1, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @ooples/token-optimizer-mcp 5.1.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @ooples/token-optimizer-mcp: affected < 5.1.0; fixed in 5.1.0

## Suggested inspection (read-only)
- `npm ls @ooples/token-optimizer-mcp --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @ooples/token-optimizer-mcp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-49mq-fc6q-3h46 (GitHub-reviewed advisory GHSA-49mq-fc6q-3h46 lists affected ranges: npm @ooples/token-optimizer-mcp >=0 <5.1.0)

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