8.8 CVE-2026-23950

Enriched by CISA
 

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.
https://nvd.nist.gov/vuln/detail/CVE-2026-23950

Categories

CWE-176 : Improper Handling of Unicode Encoding
The product does not properly handle when an input contains Unicode encoding. Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names. Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked. Server allows remote attackers to read documents outside of the web root, and possibly execute arbitrary commands, via malformed URLs that contain Unicode encoded characters. Server allows a remote attacker to obtain source code of ASP files via a URL encoded with Unicode. Overlaps interaction error.

References


 

AFFECTED (from MITRE)

Vendor Product Versions
isaacs node-tar
  • < 7.5.4 [affected]
© 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

CPE

cpe start end

REMEDIATION


EXPLOITS

Exploit-db.com

id description date
No known exploits

POC Github

Url
No known exploits

Other Nist (github, ...)

Url
No known exploits

CAPEC

Common Attack Pattern Enumerations and Classifications

id description severity
71 Using Unicode Encoding to Bypass Validation Logic
High