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How the mentioned CVE works:
The vulnerability exists in the binary fetching and extraction logic of pnpm. Attack Vector 1: When extracting downloaded ZIP files (e.g., Node.js binaries), pnpm uses the `AdmZip` library’s `extractAllTo` method. This method does not validate or sanitize paths of entries within the ZIP archive. A malicious archive containing entries with absolute paths or paths including `../` sequences (like ../../../.npmrc) will have those files written outside the intended extraction directory (nodeDir), enabling arbitrary file write. Attack Vector 2: The `BinaryResolution.prefix` field from a package’s resolution definition is directly concatenated into the file system path via `path.join(nodeDir, basename)` without validation. An attacker controlling this field (e.g., via a malicious package or registry) can set `prefix` to a path like ../../evil, causing extracted files to be written to an arbitrary location outside the targetDir.
Platform: pnpm
Version: <9.15.0
Vulnerability: Path Traversal
Severity: Critical
date: 2025-04-24
Prediction: Patch expected 2025-05-01
What Undercode Say:
$ pnpm install malicious-pkg
Code from fetching/binary-fetcher/src/index.ts
zip.extractAllTo(nodeDir, true);
Code from resolving/resolver-base/src/index.ts
const extractedDir = path.join(nodeDir, basename);
Exploit:
import zipfile
zf.writestr(‘../../../.npmrc’, …)
{
“prefix”: “../../PWNED”
}
Protection from this CVE
Update pnpm >=9.15.0.
Sanitize archive paths.
Validate `BinaryResolution.prefix`.
Impact:
Arbitrary File Write
Potential RCE
CI/CD Compromise
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
