A thunderbird security update has been released for CentOS 7.

CESA-2020:5618 Important CentOS 7 thunderbird Security Update

CentOS Errata and Security Advisory 2020:5618 Important

Upstream details at :   https://access.redhat.com/errata/RHSA-2020:5618

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

x86_64:
de7c7cd5bd6465116843083e7515695b436a00a145d6c705355b3e74a55e2b6b thunderbird-78.6.0-1.el7.centos.x86_64.rpm

Source:
507628ef1d57a01ff641a1a48d05c99111c6edb3cdf78aaaa419fd812dbc2523 thunderbird-78.6.0-1.el7.centos.src.rpm