Compressing is a compressing and uncompressing lib for node. In version 2.0.0 and 1.10.3 and prior, Compressing extracts TAR archives while restoring symbolic links without validating their targets. By embedding symlinks that resolve outside the intended extraction directory, an attacker can cause subsequent file entries to be written to arbitrary locations on the host file system. Depending on the extractor’s handling of existing files, this behavior may allow overwriting sensitive files or creating new files in security-critical locations. This issue has been patched in versions 1.10.4 and 2.0.1.

Affected: npm: compressing

# Arbitrary File Write via Symlink Extraction in `github.com/node-modules/compressing`

## Brief Introduction

The `compressing` npm package extracts TAR archives while restoring symbolic links without validating their targets. By embedding symlinks that resolve outside the intended extraction directory, an attacker can cause subsequent file entries to be written to arbitrary locations on the host file system.

Depending on the extractor’s handling of existing files, this behavior may allow overwriting sensitive files or creating new files in security-critical locations.

## Affected Component and Versions

- **Component**: `github.com/node-modules/compressing` - **Affected Versions**: `<= 1.10.3 || =2.0.0`

## Vulnerability Details

### Root Cause

`compressing.tar.uncompress` sanitizes the destination paths of archive entries, but it does **not** restrict or validate the targets of symlinks contained in TAR archives. During extraction, the library creates those symlinks inside the output directory. Later entries that resolve through the symlink are written to the symlink target rather than the intended extraction root, enabling an arbitrary file write.

### Impact

An attacker who can supply a crafted TAR archive can:

- Cause files to be written outside the intended extraction directory (arbitrary file write via symlink traversal).

- Write files to attacker-controlled paths on the host file system once symbolic links are followed during extraction.

- In environments w…