libpcre in PCRE before 8.43 allows a subject buffer over-read in JIT when UTF is disabled, and \X or \R has more than one fixed quantifier, a related issue to CVE-2019-20454.
https://www.pcre.org/original/changelog.txt
https://support.apple.com/kb/HT212147
https://support.apple.com/kb/HT211931
https://bugs.gentoo.org/717920