CVE-2026-59176
Functype: MCP set_functype_version Package Alias RCE via Unsanitized pnpm install + Dynamic Import
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.
Fixes and workarounds
Fix
functype-mcp-server (npm): OSV reports a fixed version 1.4.4. Check the advisory for supported release branches.
Source: OSV GHSA-wcjj-9m6g-2fr2Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| functype jordanburke |
< 1.4.4 (affected) | CNA: GitHub_M |
functype-mcp-serverfunctype-mcp-server
npm |
≥ 0; < 1.4.4 (affected, semver); OSV events: introduced 0; fixed 1.4.4Source events (semver)Other versions: unaffected |
OSV GHSA-wcjj-9m6g-2fr2 |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 7.8 high |
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H | CNA: GitHub_M |
Exploit evidence
- https://github.com/jordanburke/functype/security/advisories/GHSA-wcjj-9m6g-2fr2
exploit · ADP: CISA-ADP
References
- https://github.com/jordanburke/functype/security/advisories/GHSA-wcjj-9m6g-2fr2CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/jordanburke/functype/commit/c0d58ad9c2a7d15c6117bd3adbbd75de37317dcfCNA: GitHub_M · x_refsource_MISC
- https://github.com/jordanburke/functype/releases/tag/v1.4.4CNA: GitHub_M · x_refsource_MISC
- https://github.com/jordanburke/functype/security/advisories/GHSA-wcjj-9m6g-2fr2ADP: CISA-ADP · exploit
- https://github.com/advisories/GHSA-wcjj-9m6g-2fr2OSV / GitHub Security Advisories · advisory
- https://osv.dev/vulnerability/GHSA-wcjj-9m6g-2fr2OSV / GitHub Security Advisories · osv
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