encoding.c in GNU Screen through 4.8.0 allows remote attackers to cause a denial of service (invalid write access and application crash) or possibly have unspecified other impact via a crafted UTF-8 character sequence.
https://www.openwall.com/lists/oss-security/2021/02/09/3
https://www.debian.org/security/2021/dsa-4861
https://security.gentoo.org/glsa/202105-11
https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html
https://lists.debian.org/debian-lts-announce/2021/02/msg00031.html