Affected: home-assistant core

Home Assistant is open source home automation software focused on local control and privacy. Prior to 2026.2.3, the IPP integration automatically processed unauthenticated _ipp._tcp.local mDNS announcements in homeassistant/components/ipp/config_flow.py, where async_step_zeroconf passed attacker-controlled host, port, and base_path values to validate_input for printer metadata retrieval. Because the shared HTTP client followed attacker-controlled cross-origin redirects without blocking loopback targets, a local-network attacker could redirect the request to 127.0.0.1 or another internal service without user interaction or prior IPP configuration. This issue is fixed in version 2026.2.3.

Affected: PyPI: homeassistant

## Summary

Home Assistant Green is vulnerable to a Server-Side Request Forgery (SSRF) via the mDNS/Zeroconf IPP integration. An unauthenticated attacker on the local network can send a crafted mDNS response to trick Home Assistant into making HTTP requests to arbitrary hosts, including internal services bound to localhost. The IPP integration automatically processes `_ipp._tcp.local` service announcements without any user interaction or authentication, and follows HTTP redirects from the attacker-controlled host.

## Details

Home Assistant listens for mDNS service announcements on port 5353. When a service of type `_ipp._tcp.local` is discovered, the IPP integration's zeroconf handler (`homeassistant/components/ipp/config_flow.py`) processes it automatically.

The `async_step_zeroconf` method extracts `host`, `port`, and `base_path` directly from the mDNS discovery info without validation:

```python async def async_step_zeroconf( self, discovery_info: ZeroconfServiceInfo ) -> ConfigFlowResult: host = discovery_info.host port = discovery_info.port zctype = discovery_info.type name = discovery_info.name.replace(f".{zctype}", "") tls = zctype == "_ipps._tcp.local." base_path = discovery_info.properties.get("rp", "ipp/print")

self.discovery_info.update( { CONF_HOST: host, CONF_PORT: port, CONF_SSL: tls, CONF_VERIFY_SSL: False, CONF_BASE_PATH: f"/{base_path}", CONF_…