Skip to main content
← All vulnerabilities
CVE-2026-59176EUVD-2026-112078GHSA-WCJJ-9M6G-2FR2

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.4.4
None on Exploit-DB, Metasploit or GitHub

Summary

The Functype MCP server (functype-mcp-server, part of the Functype TypeScript library family) contains a flaw in its set_functype_version tool that lets a caller install an arbitrary package and then load its code, allowing attacker-supplied JavaScript to run with the server's privileges. This could let an attacker read secrets, modify files, or crash the server, and it is especially risky in HTTP-streaming deployments where the server is reachable over the network.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Read the original description

Functype is a family of TypeScript functional programming libraries. Prior to 1.4.4, the `set_functype_version` MCP tool in `functype-mcp-server` accepts an unconstrained `version` string using only `z.string()` validation in `packages/mcp-server/src/index.ts` and interpolates it into `functype@<version>` for `pnpm add`. Package-alias syntaxes such as `file:`, `npm:`, URLs, or paths can cause an arbitrary local or remote package to be installed as functype. Immediately afterward, `initDocsData(true)` in `packages/mcp-server/src/lib/docs/data.ts` resolves `functype/cli` and dynamically imports the newly installed module, executing attacker-controlled JavaScript with the MCP server process's privileges. Any MCP client able to send a `tools/call` request invoking the tool can exploit the flaw; the tool is enabled by default without authentication in `stdio` mode. A connected AI assistant susceptible to indirect prompt injection can also be induced to invoke it from a malicious document or web page. In non-default `TRANSPORT_TYPE=httpStream` deployments, a network-accessible attacker does not require local access. Successful execution can read process secrets, modify files, or terminate the server. This issue is fixed in `version` 1.4.4.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • jordanburke functype

    fixed in 1.4.4

References 3

GitHub · jordanburke/functype