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HIGH

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

Published Jan 20, 2026

Description

node-tar,a Tar for Node.js, has a race condition vulnerability in versions up to and including 7.5.3. This is due 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. 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. The patch in version 7.5.4 updates `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')`. As a workaround, 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.

Affected products

Remediation

Red Hat statement

This vulnerability is rated Important for Red Hat products. The `node-tar` library is susceptible to a race condition due to incomplete handling of Unicode path collisions, which can lead to arbitrary file overwrites via symlink poisoning. However, this issue primarily affects case-insensitive or normalization-insensitive filesystems. Red Hat Enterprise Linux and other Red Hat products typically utilize case-sensitive filesystems, which may limit the direct impact of this flaw in default configurations.

Red Hat mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Weaknesses (3)

CWE-176

CWE-352

CSRF

CWE-367

References (13)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner GitHub_M
Published Jan 20, 2026
Updated Sep 1, 2026
Reserved Jan 19, 2026
Link CVE-2026-23950
CISA Vulnrichment
Updated Jan 21, 2026
NVD
Status Modified
Modified Aug 24, 2026
Link CVE-2026-23950
Red Hat
Severity Important
Public date Jan 20, 2026
Links CVE-2026-23950 - Bugzilla
GHSA-R6Q2-HW4H-H46W