Plane: DNS Rebinding Bypass of CVE-2026-30242 SSRF Fix in Webhook Delivery

Plane is an open-source project management tool. Prior to 1.4.0, the fix for CVE-2026-30242 validates webhook IP addresses only when the webhook is created in apps/api/plane/app/serializers/webhook.py. The delivery task in apps/api/plane/bgtasks/webhook_task.py performs a separate DNS resolution when sending the request and does not validate the resolved IP address, allowing DNS rebinding to bypass the SSRF protection. This issue is fixed in 1.4.0.