# CVE-2026-23950

## Summary

- **CVE ID:** CVE-2026-23950
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L)
- **CWE:** CWE-176, CWE-352, CWE-367
- **Published:** Jan 20, 2026
- **Last Modified:** Sep 1, 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

- isaacs — node-tar (< 7.5.4)

## References

- [CNA](https://github.com/isaacs/node-tar/security/advisories/GHSA-r6q2-hw4h-h46w)
- [CNA](https://github.com/isaacs/node-tar/commit/3b1abfae650056edfabcbe0a0df5954d390521e6)
- [redhat-SADP](https://access.redhat.com/security/cve/CVE-2026-23950)
- [redhat-SADP](https://bugzilla.redhat.com/show_bug.cgi?id=2431036)
- [redhat-SADP](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23950.json)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:18480)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:18868)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:6192)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:2926)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:2144)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.24%
- **EPSS Percentile:** 14.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-12._