CVE-2026-34590 Postiz: SSRF via Webhook Creation Endpoint Missing URL Safety Validation

Postiz is an AI social media scheduling tool. Prior to version 2.21.4, the POST /webhooks/ endpoint for creating webhooks uses WebhooksDto which validates the url field with only @IsUrl format check, missing the @IsSafeWebhookUrl validator that blocks internal/private network addresses. The updat...