Keep it buttoned up friends. Apple doesn't give (m)any details... more below
https://techcrunch.com/2021/09/13/apple-zero-day-nso-pegasus/
https://us-cert.cisa.gov/ncas/current-activity/2021/09/13/apple-releases-security-updates-address-cve-2021-30858-and-cve
https://www.cnn.com/2021/09/13/tech/apple-iphone-spyware-vulnerability-fix/index.html