# Zip Slip (Archive Path Traversal)

> Detects insecure ZIP/TAR extraction that does not validate entry paths, allowing directory traversal outside the extraction target.

- Skill: `zakirkun/zip-slip-archive-path-traversal` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add zakirkun/zip-slip-archive-path-traversal`
- Raw SKILL.md: https://api.skillmd.com/api/skills/zakirkun/zip-slip-archive-path-traversal/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: zakirkun (https://skillmd.com/u/zakirkun)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/zakirkun/zip-slip-archive-path-traversal

---


# Zip Slip (Archive Path Traversal)

## Overview
Zip Slip is a directory traversal vulnerability in archive extraction. Malicious archives can contain entry names like `../../etc/cron.d/evil` or `../webroot/shell.php`. When extracted without path validation, files are written outside the intended directory, potentially achieving:
- Remote Code Execution (writing to cron, web shell in webroot)
- Configuration overwrite
- Sensitive file replacement

This affects ZIP, TAR, JAR, WAR, and other archive formats.

## Detection Strategy
- `ZipFile.extractall()` in Python without path validation
- `unzip.extract()` in Java without checking entry name for `..`
- `archive.ExtractAll()` in Go without normalized path check

## Remediation
Always normalize and validate the target path before writing each archive entry.

**Vulnerable (Java):**
```java
ZipEntry entry = zipFile.getEntry(name);
File dest = new File(targetDir, entry.getName());
// entry.getName() could be "../../etc/cron.d/evil"
```

**Safe (Java):**
```java
File dest = new File(targetDir, entry.getName()).getCanonicalFile();
if (!dest.toPath().startsWith(targetDir.toPath())) {
    throw new IOException("Zip Slip detected: " + entry.getName());
}
```