Prior to 2026.2.3, the IPP integration in Home Assistant automatically processed unauthenticated mDNS announcements for the service _ipp._tcp.local. The integration passed the attacker‑controlled host, port, and base_path values to the printer metadata retrieval function without validating them. Because the internal HTTP client followed cross‑origin redirects without blocking loopback targets, an attacker able to inject a spoofed mDNS advertisement could engineer the client to issue a request to 127.0.0.1 or another internal endpoint, exposing local services or sensitive information without user interaction or prior configuration. The vulnerability is a classic Server‑Side Request Forgery (CWE‑918).

The affected product is Home Assistant Core. Any installation of Home Assistant Core older than version 2026.2.3 is vulnerable. The fix was released in the 2026.2.3 release; versions prior to that release expose the system to the described risk.

The CVSS score of 5.4 indicates a moderate severity, and the vulnerability can be exploited from any device on the same local network segment that can send mDNS packets to the Home Assistant host. Although EPSS is not available, attackers who have access to the local network can construct the malicious injection without needing elevated privileges or direct access to the Home Assistant configuration. The issue is not currently listed in the CISA KEV catalog, but because it can lead to unauthorized access to internal services, the threat remains significant for environments where internal services are unprotected.