Title: CVE-2018-6871 Remote arbitrary file disclosure vulnerability via WEBSERVICE formula

Announced: February 9, 2018

Fixed in: LibreOffice 5.4.5/6.0.1


LibreOffice before 5.4.5 and 6.x before 6.0.1 allows remote attackers to read arbitrary files via =WEBSERVICE calls in a document, which use the COM.MICROSOFT.WEBSERVICE function.

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.

All users are recommended to upgrade to LibreOffice >= 5.4.5 or >= 6.0.1