CVE-2026-84697 [MEDIUM] – Mailpit’s IsInternalIP deny list function fails to block the Azure WireServer address 168.

Mailpit’s IsInternalIP deny list function fails to block the Azure WireServer address 168.63.129.16 and the RFC 2765/6145 IPv4-translated IPv6 prefix, allowing server-side request forgery to internal destinations. Attackers can supply hostnames resolving to these addresses in message content to reach the link check API and proxy endpoint for accessing internal resources.