Title: CVE-2017-3157 Arbitrary file disclosure in Calc and Writer
Announced: February 22, 2017
Fixed in: LibreOffice 5.1.6/5.2.2/5.3.0
Embedded Objects in writer and calc can contain previews of their content. A document can be crafted which contains an embedded object that is a link to an existing file on the targets system. On load the preview of the embedded object will be updated to reflect the content of the file on the target system. In the case of LibreOffice used as an online service that preview of data on the target system could be used to expose details of the environment LibreOffice is running in. In the case of LibreOffice as a standard desktop application, the preview could be concealed in hidden sections and retrieved by the attacker if the document is saved and returned to sender.
In later version of LibreOffice without this flaw the LinkUpdateMode feature has been expanded to additionally control the update of previews of embedded objects as well as its prior function to control the update of embedded object contents.
All users are recommended to upgrade to LibreOffice >= 5.1.6 or >= 5.2.5 or >= 5.3.0
Thanks to Ben Hayak for discovering this flaw.