LibreOffice -- Remote arbitrary file disclosure vulnerability via WEBSERVICE formula

LibreOffice reports:

LibreOffice Calc supports a WEBSERVICE function to obtain data by URL.
Vulnerable versions of LibreOffice allow WEBSERVICE to take a local file
URL (e.g file://) which can be used to inject local files into the
spreadsheet without warning the user. Subsequent formulas can operate on
that inserted data and construct a remote URL whose path leaks the local
data to a remote attacker.
In later versions of LibreOffice without this flaw, WEBSERVICE has now
been limited to accessing http and https URLs along with bringing
WEBSERVICE URLs under LibreOffice Calc’s link management infrastructure.
Note: This vulnerability has been identified upstream
as CVE-2018-1055, but NVD/Mitre are advising it’s a reservation
duplicate of CVE-2018-6871 which should be used instead.