CVE-2026-46678

Affected versions of the pydantic-ai package are vulnerable to Server-Side Request Forgery due to the cloud-metadata and private-IP blocklists failing to handle IPv6 transition representations of blocked IPv4 endpoints. When an application opts a FileUrl, ImageUrl, AudioUrl, VideoUrl, or DocumentUrl into force_download='allow-local', the existing blocklist does not recognise IPv4-mapped IPv6 addresses, 6to4 addresses, or the NAT64 well-known prefix that resolve to cloud-metadata IPs on dual-stack or translated networks. An attacker who can influence such a URL with untrusted input can bypass the parent advisory metadata block and retrieve short-term IAM credentials from the cloud-metadata endpoint.