An expat security update has been released for CentOS 7.

CESA-2022:6834 Important CentOS 7 expat Security Update

CentOS Errata and Security Advisory 2022:6834 Important

Upstream details at :   https://access.redhat.com/errata/RHSA-2022:6834

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

x86_64:
fc2d6ed7481cb42c62b4bd75126fc4237093c74ba7e87908a90815f672bdf45d expat-2.1.0-15.el7_9.i686.rpm
6cc655263da0213df7eb5a2c6c63b5825361f55336855a67a7b33881d10ca955 expat-2.1.0-15.el7_9.x86_64.rpm
8246ba658ab0a84cdf2b467c142701ec560b9ced3db90dfd04a7275cb2636566 expat-devel-2.1.0-15.el7_9.i686.rpm
45f0406fbbb55abe1511ceade8ca9fb297ae44cce197166c9a3f70561dbffc30 expat-devel-2.1.0-15.el7_9.x86_64.rpm
38165265e6956a27cc026b542a5b84342b4e8d479263713e10c9a0b0871d9705 expat-static-2.1.0-15.el7_9.i686.rpm
77a2ace1d206cdce59078a04e1d50602e60fa9783490a87d7d894bfb57c1904c expat-static-2.1.0-15.el7_9.x86_64.rpm

Source:
d70e3bdce754b49decc74f25383590b56b46b4726a5069d396c62f9fe4ae3db9 expat-2.1.0-15.el7_9.src.rpm