A thunderbird security update has been released for CentOS 7.

CentOS-announce: CESA-2020:1489 Important CentOS 7 thunderbird Security Update

CentOS Errata and Security Advisory 2020:1489 Important

Upstream details at :   https://access.redhat.com/errata/RHSA-2020:1489

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

x86_64:
c1f729bd646d786b455ced02fdef3ba707209d19abbe2e9248afe1d5a9d619e4 thunderbird-68.7.0-1.el7.centos.x86_64.rpm

Source:
089d5be107c79b4090a94a85a7eb10266faa859fe4a4cac0ef4dbd418f1946f8 thunderbird-68.7.0-1.el7.centos.src.rpm