ultralytics/yolov5 · error · ValueError

Blocked request to internal address: {addr}

Error message

Blocked request to internal address: {addr}

What it means

_validate_ssrf_url raises ValueError when the hostname resolves to an IP classified as private, loopback, link-local, reserved, or multicast. This is the SSRF guard: YOLOv5 download paths refuse to fetch from internal addresses so a malicious URL (e.g. in a crafted data yaml 'download:' field) cannot reach cloud metadata endpoints or intranet services. The check inspects every address returned by getaddrinfo and every redirect hop.

Source

Thrown at models/common.py:827

    def _load_metadata(f=Path("path/to/meta.yaml")):
        """Loads metadata from a YAML file, returning strides and names if the file exists, otherwise `None`."""
        if f.exists():
            d = yaml_load(f)
            return d["stride"], d["names"]  # assign stride, names
        return None, None


def _validate_ssrf_url(url: str) -> None:
    """Raise ValueError if url resolves to any private/internal address."""
    hostname = urlparse(url).hostname or ""
    try:
        results = socket.getaddrinfo(hostname, None)
    except socket.gaierror as e:
        raise ValueError(f"Could not resolve hostname '{hostname}': {e}") from e
    for _family, _type, _proto, _canonname, sockaddr in results:
        addr = ipaddress.ip_address(sockaddr[0])
        if addr.is_private or addr.is_loopback or addr.is_link_local or addr.is_reserved or addr.is_multicast:
            raise ValueError(f"Blocked request to internal address: {addr}")


def _request_ssrf_url(url: str, max_redirects: int = 5):
    """Fetch a URL after validating each resolved redirect target."""
    session = requests.Session()
    for _ in range(max_redirects + 1):
        _validate_ssrf_url(url)
        response = session.get(url, stream=True, allow_redirects=False)
        if not response.is_redirect:
            return response
        url = urljoin(response.url, response.headers["location"])
        response.close()
    raise ValueError(f"Too many redirects while fetching {url}")


class AutoShape(nn.Module):
    """AutoShape class for robust YOLOv5 inference with preprocessing, NMS, and support for various input formats."""

View on GitHub (pinned to 20d1d78a08)

Solutions

1. Use a public URL for downloads, or download the file yourself and pass the local path — local files bypass the URL validator.
2. If an internal mirror is required, fetch it outside this code path (curl/wget) and reference the local file.
3. Audit any third-party data yaml for its download: value before running train.py on it.
4. Do not attempt to disable the guard; it is intentional protection for untrusted yaml input.

Example fix

# before (blocked by SSRF guard)
# data.yaml: download: http://10.20.30.40/coco128.zip

# after
# wget http://10.20.30.40/coco128.zip -O ~/datasets/coco128.zip, then point data.yaml paths at the local copy

import socket, ipaddress
from urllib.parse import urlparse

def url_is_public(url: str) -> bool:
    host = urlparse(url).hostname or ''
    try:
        addrs = [sockaddr[0] for *_m, sockaddr in socket.getaddrinfo(host, None)]
    except socket.gaierror:
        return False
    def bad(a):
        x = ipaddress.ip_address(a)
        return x.is_private or x.is_loopback or x.is_link_local or x.is_reserved or x.is_multicast
    return not any(bad(a) for a in addrs)

try:
    _request_ssrf_url(url)
except ValueError as e:
    if 'Blocked request to internal address' in str(e):
        raise SystemExit('Internal URLs are blocked by design; download manually and use a local path') from e

When it happens

Trigger: A data yaml with download: http://10.0.0.5/dataset.zip or http://localhost:8000/data.zip; a URL whose public-looking hostname DNS-rebinds to 169.254.169.254; a redirect from a public host to an internal one; legitimately using an internal mirror to serve weights.

Common situations: Corporate environments hosting datasets on internal NAS/IPs; self-hosted artifact mirrors (Nexus, Artifactory on a LAN IP); security testing of untrusted yaml files; attempts to use 127.0.0.1 for local testing of download flows.

Related errors

• Could not resolve hostname '{hostname}': {e}
• Too many redirects while fetching {url}
• {e}. Cache may be out of date, try `force_reload=True` or se
• Dataset not found ❌

AI-assisted analysis of ultralytics/yolov5@20d1d78a08 (2026-08-15). Data as JSON: /api/errors/8f220201d7061e7e. Report an issue: GitHub.