The validators.ipv6(ip, private=True) call always returns a falsy ValidationError because validators==0.35.0 does not support the private kwarg for IPv6. This means any hostname resolving to a private IPv6 address (::1, fd00::*, ::ffff:169.254.169.254) bypasses SSRF protection entirely, circumventing the fix for CVE-2025-65958.
Replace both the IPv4 and IPv6 validators-based private checks with Python's stdlib ipaddress module using an allowlist approach (not addr.is_global). This blocks all non-globally-routable addresses — private, loopback, link-local, reserved, multicast, and unspecified — for both IPv4 and IPv6, including IPv4-mapped IPv6 addresses.