--- cve: "CVE-2026-23950" severity: "HIGH" cvss: 8.8 epss: "23%" vendor: "isaacs" kev: false exploited: false published: "2026-01-20 01:15:57" tags: [cve, security, high] source: tsecurity.de CVE-Dossier exported: "2026-09-08T11:28:03+02:00" --- # CVE-2026-23950 > 8.8 HIGH · 🧪 PoC ## Beschreibung 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-Vektor ``` CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L ``` | Metrik | Wert | Bewertung | |---|---|---| | AV Angriffsvektor | Netzwerk | bad | | AC Komplexität | Gering | bad | | PR Privilegien | Keine | bad | | UI Interaktion | Erforderlich | good | | S Scope | Verändert | bad | | C Vertraulichkeit | Gering | warn | | I Integrität | Hoch | bad | | A Verfügbarkeit | Gering | warn | ## Patch verfügbar (OSV) - 911c886bb170a6ee3db05fd3709221752213ec8a (Commit) - 3b1abfae650056edfabcbe0a0df5954d390521e6 (Commit) ## Referenzen - - - - - - - - - - --- _Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-23950) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_