A thunderbird security update has been released for CentOS 7.

CESA-2021:3160 Important CentOS 7 thunderbird Security Update

CentOS Errata and Security Advisory 2021:3160 Important

Upstream details at :   https://access.redhat.com/errata/RHSA-2021:3160

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

x86_64:
245ac011d84f87d216206c87c125f53accc51bf59e77b4f325bd2519bbae562a thunderbird-78.13.0-1.el7.centos.src.rpm
d358a86339e24e16bfcc77c61f6f12dea5c1485847a4bd5eee6a6e06c3634ff2 thunderbird-78.13.0-1.el7.centos.x86_64.rpm