A xorg-x11-server security update has been released for CentOS 7.

CESA-2021:2033 Important CentOS 7 xorg-x11-server Security Update

CentOS Errata and Security Advisory 2021:2033 Important

Upstream details at :   https://access.redhat.com/errata/RHSA-2021:2033

The following updated files have been uploaded and are currently
syncing to the mirrors: ( sha256sum Filename )

x86_64:
96e84480f4e5f3ed973231a88b1834dd30e01f9cb98655b8551b7d1f382b024f xorg-x11-server-common-1.20.4-16.el7_9.x86_64.rpm
d24805d0f00f2158a082be3fd450a90be7ca614871fb70850db6aa028a020d87 xorg-x11-server-devel-1.20.4-16.el7_9.i686.rpm
a2b140586a9cd6744d897271b92c1c28166d43a99eb058d831c0617399959558 xorg-x11-server-devel-1.20.4-16.el7_9.x86_64.rpm
d893452495f6ed739d82236d307ce20f1ee7fb06ea522109fca58008ef041452 xorg-x11-server-source-1.20.4-16.el7_9.noarch.rpm
cf170bfe59fb4723dcf9f79d8e4e924c16926a7fa50ee45988c38123421bfff3 xorg-x11-server-Xdmx-1.20.4-16.el7_9.x86_64.rpm
a83c7d173d50416c52930bc2a1c8a136889066cddd068990b84f0ed6f341dfac xorg-x11-server-Xephyr-1.20.4-16.el7_9.x86_64.rpm
a2f9c00b20dcf7207991f467a8714eb3d7273d424ee4dd045d1a5232da5cd797 xorg-x11-server-Xnest-1.20.4-16.el7_9.x86_64.rpm
cf01690bbc873920b5a486d4d4e6b92160ae532f81d1ce1045c632c8c0c68aae xorg-x11-server-Xorg-1.20.4-16.el7_9.x86_64.rpm
ae1aa9868c275415bf9db1de0d9e270cf72ea7011a3c350bcb6efc29acb3b953 xorg-x11-server-Xvfb-1.20.4-16.el7_9.x86_64.rpm
ec5ec6e21071682dfbc3c256617c810c886af178cfc7f21a96104cf10ee6cb25 xorg-x11-server-Xwayland-1.20.4-16.el7_9.x86_64.rpm

Source:
35fad26658aefa76dde010d930a862c164d7e37049f333fc87f3897f68ec5221 xorg-x11-server-1.20.4-16.el7_9.src.rpm