Evolver is a GEP-powered self-evolving engine for AI agents. Prior to version 1.69.3, a path traversal vulnerability in the skill download (fetch) command allows attackers to write files to arbitrary locations on the filesystem. The --out= flag accepts user-provided paths without validation, enabling directory traversal attacks that can overwrite critical system files or create files in sensitive location. This issue has been patched in version 1.69.3.

Affected: npm: @evomap/evolver

### Summary A path traversal vulnerability in the skill download (`fetch`) command allows attackers to write files to arbitrary locations on the filesystem. The `--out=` flag accepts user-provided paths without validation, enabling directory traversal attacks that can overwrite critical system files or create files in sensitive locations.

### Details The vulnerability exists in `index.js` at lines 752-767:

```javascript // index.js:751-768 const outFlag = args.find(a => typeof a === 'string' && a.startsWith('--out=')); const safeId = String(data.skill_id || skillId).replace(/[^a-zA-Z0-9_\-\.]/g, '_');

// VULNERABLE: No path validation on user input const outDir = outFlag ? outFlag.slice('--out='.length) // User-controlled path : path.join('.', 'skills', safeId);

if (!fs.existsSync(outDir)) fs.mkdirSync(outDir, { recursive: true });

// ... downloads skill files to outDir ```

The `outFlag.slice('--out='.length)` extracts the user-provided path without any sanitization or validation. An attacker can provide paths like `../../../etc/cron.d` to write files outside the intended directory.

Note: The `safeId` variable is sanitized via inline replacement (`replace(/[^a-zA-Z0-9_\-\.]/g, '_')`), but this sanitization only applies to the default path, not to the user-provided `--out=` path.

### PoC

**Prerequisites:** - Node.js installed - Access to the evolver application

**Steps to reproduce:**

1. Create a test file demonstrating the vulnerability:

```javascript // tes…