An integer overflow was addressed with improved input validation. This issue is fixed in Security Update 2021-005 Catalina, iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6, watchOS 7.6.2. Processing a maliciously crafted PDF may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.
seclists.org/fulldisclosure/2021/Sep/25
seclists.org/fulldisclosure/2021/Sep/26
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seclists.org/fulldisclosure/2021/Sep/40
seclists.org/fulldisclosure/2021/Sep/50
www.openwall.com/lists/oss-security/2022/09/02/11
security.gentoo.org/glsa/202209-21
support.apple.com/en-us/HT212804
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support.apple.com/kb/HT212824