From https://nvd.nist.gov/vuln/detail/CVE-2021-30184:

GNU Chess 6.2.7 allows attackers to execute arbitrary code via crafted PGN
(Portable Game Notation) data. This is related to a buffer overflow in the use
of a .tmp.epd temporary file in the cmd_pgnload and cmd_pgnreplay functions in
frontend/cmd.cc.

Upstream bug report and patch:
https://lists.gnu.org/archive/html/bug-gnu-chess/2021-04/msg00000.html

Upstream is aware of this issue and patch.  The patch is being reviewed upstream:

Response by Antonio Ceballos (<https://lists.gnu.org/archive/html/bug-gnu-chess/2021-04/msg00001.html>)
‘We will review it all in detail for a future release fixing the problem.’

I believe we should simply wait for upstream to make a release.