node-tar: Process crash via PAX numeric path type confusion

Exploitation

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

CVSS

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

EPSS

• CVE-2026-59871: 0.64% estimated exploitation activity in the next 30 days; percentile 50.92 (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 crafted 2.5KB tar archive crashes any Node.js process that extracts it. The PAX header parser coerces all-digit path values to JavaScript numbers, which causes an uncaught TypeError when downstream code calls .split('/') on the numeric value. Error handlers and strict: false cannot intercept the crash. Details In pax.ts line 180, parseKV converts PAX values matching /^[0-9]+$/ to numbers via +v. This applies to all fields including path and linkpath. When a PAX header sets path to an all-digit string like "12345", the value becomes the number 12345. This number flows through Header - ReadEntry - Unpack.CHECKPATH, where normalizeWindowsPath(entry.path).split('/') throws a TypeError because numbers don't have .split(). The throw is synchronous during event emission and bypasses all error handling: - strict: false does not help - 'error' event handlers do not catch it - 'warn' handlers do not catch it - The TypeError propagates through the event emitter stack as an…

Published by the source

20 Jul 2026, 21:53 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 12:57 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-w8wr-v893-vjvp

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-w8wr-v893-vjvp

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# Patch Next advisory brief: CVE-2026-59871

Advisory: node-tar: Process crash via PAX numeric path type confusion
IDs: CVE-2026-59871, GHSA-w8wr-v893-vjvp
Record: https://patchnext.com/advisories/cve-2026-59871 (revision 2, source checked 26 Oct 2026, 12:57 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tar 7.5.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm tar: affected <= 7.5.17; fixed in 7.5.18

## Suggested inspection (read-only)
- `npm ls tar --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 tar.
- 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-w8wr-v893-vjvp (OSV record GHSA-w8wr-v893-vjvp lists affected ranges: npm tar >=0 <7.5.18 (fixed))
- Verified: https://github.com/advisories/GHSA-w8wr-v893-vjvp (GitHub-reviewed advisory GHSA-w8wr-v893-vjvp lists affected ranges: npm tar >=0 <=7.5.17)

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