International Components for Unicode (ICU-20850) v66.1 was discovered to contain a use after free bug in the pkg_createWithAssemblyCode function in the file tools/pkgdata/pkgdata.cpp.
https://www.debian.org/security/2021/dsa-5014
https://unicode-org.atlassian.net/browse/ICU-20850
https://lists.debian.org/debian-lts-announce/2021/10/msg00008.html