Race Condition in node-tar Path Reservations via Unicode Ligature Collisions on macOS APFS

Exploitation

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

CVSS

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

EPSS

• CVE-2026-23950: 0.26% estimated exploitation activity in the next 30 days; percentile 18.37 (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.

TITLE: Race Condition in node-tar Path Reservations via Unicode Sharp-S (ß) Collisions on macOS APFS AUTHOR: Tomás Illuminati Details A race condition vulnerability exists in node-tar (v7.5.3) this is to an incomplete handling of Unicode path collisions in the path-reservations system. On case-insensitive or normalization-insensitive filesystems (such as macOS APFS, In which it has been tested), the library fails to lock colliding paths (e.g., ß and ss), allowing them to be processed in parallel. This bypasses the library's internal concurrency safeguards and permits Symlink Poisoning attacks via race conditions. The library uses a PathReservations system to ensure that metadata checks and file operations for the same path are serialized. This prevents race conditions where one entry might clobber another concurrently. In MacOS the FS confuses ß with ss, but this code does not. For example: bash bash-3.2$ printf "CONTENTSS\n" collisiontestss bash-3.2$ ls collisiontestss bash-3.2$…

Published by the source

21 Jan 2026, 01:05 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r6q2-hw4h-h46w

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-r6q2-hw4h-h46w

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# Patch Next advisory brief: CVE-2026-23950

Advisory: Race Condition in node-tar Path Reservations via Unicode Ligature Collisions on macOS APFS
IDs: CVE-2026-23950, GHSA-r6q2-hw4h-h46w
Record: https://patchnext.com/advisories/cve-2026-23950 (revision 2, source checked 26 Oct 2026, 12:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tar 7.5.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm tar: affected <= 7.5.3; fixed in 7.5.4

## 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-r6q2-hw4h-h46w (OSV record GHSA-r6q2-hw4h-h46w lists affected ranges: npm tar >=0 <7.5.4 (fixed))
- Verified: https://github.com/advisories/GHSA-r6q2-hw4h-h46w (GitHub-reviewed advisory GHSA-r6q2-hw4h-h46w lists affected ranges: npm tar >=0 <=7.5.3)

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