--- title: "CVE-2026-23950\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2026-23950?format=md keywords: index, follow --- # CVE-2026-23950 Publication date 20 January 2026 Last updated 21 January 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **8.8 · High** [Score breakdown](https://ubuntu.com/security/CVE-2026-23950?format=md#impact-score) Toggle side navigation ## 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. ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | node-tar | 26.04 LTS resolute | Needs evaluation | | 25.10 questing | Ignored end of life, was needs-triage | | 24.04 LTS noble | Needs evaluation | | 22.04 LTS jammy | Needs evaluation | | 20.04 LTS focal | Needs evaluation | | 18.04 LTS bionic | Needs evaluation | | 16.04 LTS xenial | Needs evaluation | | 14.04 LTS trusty | Needs evaluation | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 8.8 · High * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Privileges required | None | | User interaction | Required | | Scope | Changed | | Confidentiality impact | Low | | Integrity impact | High | | Availability impact | Low | * Scores | Parameter | Value | | --- | --- | | Base score | 8.8 · High | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-23950) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-23950) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-23950) * [Debian](https://security-tracker.debian.org/tracker/CVE-2026-23950) ### Other references * * * *