This indicates an attack attempt to exploit an Information Disclosure Vulnerability in Apple Safari WebKit.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted webpage. Successful exploitation could result in disclosure of sensitive information which could be used to further compromise the target system.
Apple iOS before 13.4
Apple iPadOS before 13.4
Apple tvOS before 13.4
Apple Safari before 13.1
Apple iTunes for Windows before 12.10.5
Apple iCloud for Windows before 10.9.3
Apple iCloud for Windows before 7.18
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.