Core:
    Fixed bug #81302 (Stream position after stream filter removed).
    Fixed bug #81346 (Non-seekable streams don't update position after write).
    Fixed bug #73122 (Integer Overflow when concatenating strings).
GD:
    Fixed bug #53580 (During resize gdImageCopyResampled cause colors change).
Opcache:
    Fixed bug #81353 (segfault with preloading and statically bound closure).
Shmop:
    Fixed bug #81407 (shmop_open won't attach and causes php to crash).
Standard:
    Fixed bug #71542 (disk_total_space does not work with relative paths).
    Fixed bug #81400 (Unterminated string in dns_get_record() results).
SysVMsg:
    Fixed bug #78819 (Heap Overflow in msg_send).
XML:
    Fixed bug #81351 (xml_parse may fail, but has no error code).
Zip:
    Fixed bug #81420 (ZipArchive::extractTo extracts outside of destination). (CVE-2021-21706)