CVE-2026-23950

Aliases:GHSA-r6q2-hw4h-h46w
Advisory lineage Upstream: 0 Downstream: 4
Analyzed
Published: 20 Jan 2026, 00:40
Last modified:15 Jul 2026, 01:17

Vulnerability Summary

Overall Risk (default)
medium
45/100
CVSS Score
8.8 HIGH
v3.1 (cve.org)
EPSS Score
0.23% LOW
0% probability +0.22%
KEV
Not listed
Ransomware
No reports
Public exploits
1 found
Dark Web
Not detected

Timeline

20 Jan 2026, 00:40
Published
Vulnerability first disclosed
15 Jul 2026, 01:17
Last Modified
Vulnerability information updated

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.

CVSS Metrics

  • v3.1•HIGH•Score: 8.8CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
  • v3.1•MEDIUM•Score: 5.9CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Trends

Current EPSS score: 0.23%• Percentile: 14%

Techniques & Countermeasures

  • CWE-176•Improper Handling of Unicode Encoding

    The product does not properly handle when an input contains Unicode encoding.

  • CWE-352•Cross-Site Request Forgery (CSRF)

    The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.

  • CWE-367•Time-of-check Time-of-use (TOCTOU) Race Condition

    The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

Affected Systems

  • isaacs•node-tar

    < 7.5.4

  • isaacs•tar

    < 7.5.4

  • Npm•tar

    < 7.5.4

References (12)