functype-mcp-server: MCP set_functype_version Package Alias RCE via Unsanitized pnpm install + Dynamic Import

Exploitation

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

CVSS

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

EPSS

• CVE-2026-59176: 0.21% estimated exploitation activity in the next 30 days; percentile 11.47 (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.

MCP `set_functype_version` Package Alias RCE via Unsanitized pnpm install + Dynamic Import

Summary The `set_functype_version` MCP tool in `functype-mcp-server` accepts an unconstrained `version` string, interpolates it directly into an npm package specifier (`functype@ `), and installs it via `pnpm add` without any validation. Because npm/pnpm package specifiers support `file:`, `npm:`, and other alias syntaxes, an attacker who can send an MCP `tools/call` request to this tool can cause the server to install an arbitrary local or remote package as `functype`. Immediately after installation, the server calls `initDocsData(true)`, which dynamically imports `functype/cli` from the newly installed location, executing attacker-controlled JavaScript in the MCP server process. This results in full Remote Code Execution (RCE) with the privileges of the server process — full confidentiality, integrity, and availability impact (CVSS 7.8 High).

Details The vulnerable code is in…

Published by the source

9 Sep 2026, 23:49 UTC

Last modified by the source

2 Nov 2026, 19:45 UTC

Source last checked

3 Nov 2026, 06:00 UTC

1. Revision 5 · amended · 3 Nov 2026

   Amended from osv record GHSA-wcjj-9m6g-2fr2

2. Revision 4 · amended · 2 Nov 2026

   Amended from ghsa record GHSA-wcjj-9m6g-2fr2

3. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-wcjj-9m6g-2fr2

4. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-wcjj-9m6g-2fr2

5. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-wcjj-9m6g-2fr2

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# Patch Next advisory brief: CVE-2026-59176

Advisory: functype-mcp-server: MCP `set_functype_version` Package Alias RCE via Unsanitized pnpm install + Dynamic Import
IDs: CVE-2026-59176, GHSA-wcjj-9m6g-2fr2
Record: https://patchnext.com/advisories/cve-2026-59176 (revision 5, source checked 3 Nov 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: functype-mcp-server 1.4.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm functype-mcp-server: affected < 1.4.4; fixed in 1.4.4

## Suggested inspection (read-only)
- `npm ls functype-mcp-server --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 functype-mcp-server.
- 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-wcjj-9m6g-2fr2 (GitHub-reviewed advisory GHSA-wcjj-9m6g-2fr2 lists affected ranges: npm functype-mcp-server >=0 <=1.4.3)
- Verified: https://osv.dev/vulnerability/GHSA-wcjj-9m6g-2fr2 (OSV record GHSA-wcjj-9m6g-2fr2 lists affected ranges: npm functype-mcp-server >=0 <1.4.4 (fixed))

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