CVE-2026-76239 Stigmem before 0.9.0a11 SSRF via unvalidated webhook delivery_address

Stigmem before 0.9.0a11 fails to validate the deliveryaddress parameter when creating webhook subscriptions, allowing authenticated users to specify internal loopback and private network destinations. Attackers can trigger matching fact-change events to cause the Stigmem server to issue server-si...