The updated packages fix security vulnerabilities:
Use-after-free in xmlEncodeEntitiesInternal() in entities.c. (CVE-2021-3516)
Heap-based buffer overflow in xmlEncodeEntitiesInternal() in entities.c. (CVE-2021-3517)
Use-after-free in xmlXIncludeDoProcess() in xinclude.c. (CVE-2021-3518)
NULL pointer dereference in valid.c in xmlValidBuildAContentModel. (CVE-2021-3537)