pnpm: Binary ZIP extraction allows arbitrary file write via path traversal (Zip Slip)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-23888: 0.45% estimated exploitation activity in the next 30 days; percentile 39.17 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A path traversal vulnerability in pnpm's binary fetcher allows malicious packages to write files outside the intended extraction directory. The vulnerability has two attack vectors: (1) Malicious ZIP entries containing ../ or absolute paths that escape the extraction root via AdmZip's extractAllTo, and (2) The BinaryResolution.prefix field is concatenated into the extraction path without validation, allowing a crafted prefix like ../../evil to redirect extracted files outside targetDir. Details The vulnerability exists in the binary fetching and extraction logic: 1. Unvalidated ZIP Entry Extraction (fetching/binary-fetcher/src/index.ts) AdmZip's extractAllTo does not validate entry paths for path traversal: A ZIP entry with path ../../../.npmrc will be written outside nodeDir. 2. Unvalidated Prefix in BinaryResolution (resolving/resolver-base/src/index.ts) The basename variable comes from BinaryResolution.prefix and is used directly in path construction: PoC Attack Vector 1:…

Published by the source

26 Jan 2026, 21:02 UTC

Last modified by the source

3 Feb 2026, 03:06 UTC

Source last checked

26 Oct 2026, 12:41 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-6pfh-p556-v868

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-6pfh-p556-v868

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# Patch Next advisory brief: CVE-2026-23888

Advisory: pnpm: Binary ZIP extraction allows arbitrary file write via path traversal (Zip Slip)
IDs: CVE-2026-23888, GHSA-6pfh-p556-v868
Record: https://patchnext.com/advisories/cve-2026-23888 (revision 2, source checked 26 Oct 2026, 12:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pnpm 10.28.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm pnpm: affected < 10.28.1; fixed in 10.28.1

## Suggested inspection (read-only)
- `npm ls pnpm --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pnpm.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-6pfh-p556-v868 (OSV record GHSA-6pfh-p556-v868 lists affected ranges: npm pnpm >=0 <10.28.1 (fixed))
- Verified: https://github.com/advisories/GHSA-6pfh-p556-v868 (GitHub-reviewed advisory GHSA-6pfh-p556-v868 lists affected ranges: npm pnpm >=0 <10.28.1)

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