In PHP versions 7.1.x below 7.1.33, 7.2.x below 7.2.24 and 7.3.x below 7.3.11 in certain configurations of FPM setup it is possible to cause FPM module to write past allocated buffers into the space reserved for FCGI protocol data, thus opening the possibility of remote code execution.
https://www.tenable.com/security/tns-2021-14
https://www.synology.com/security/advisory/Synology_SA_19_36
https://www.debian.org/security/2019/dsa-4553
https://www.debian.org/security/2019/dsa-4552
https://usn.ubuntu.com/4166-2/
https://usn.ubuntu.com/4166-1/
https://support.f5.com/csp/article/K75408500?utm_source=f5support&%3Butm_medium=RSS
https://support.apple.com/kb/HT210919
https://security.netapp.com/advisory/ntap-20191031-0003/
https://seclists.org/bugtraq/2020/Jan/44
https://github.com/neex/phuip-fpizdam
https://bugs.php.net/bug.php?id=78599
https://access.redhat.com/errata/RHSA-2020:0322
https://access.redhat.com/errata/RHSA-2019:3736
https://access.redhat.com/errata/RHSA-2019:3735
https://access.redhat.com/errata/RHSA-2019:3724
https://access.redhat.com/errata/RHSA-2019:3300
https://access.redhat.com/errata/RHSA-2019:3299
https://access.redhat.com/errata/RHSA-2019:3287
https://access.redhat.com/errata/RHSA-2019:3286
http://seclists.org/fulldisclosure/2020/Jan/40
http://packetstormsecurity.com/files/156642/PHP-FPM-7.x-Remote-Code-Execution.html
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00014.html
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00011.html