This indicates an attack attempt to exploit an Information Disclosure Vulnerability in Libreoffice.
A remote attacker could exploit the vulnerability by enticing a user to open a specially crafted ODS document. Successful exploitation could result in disclosure of information which could be used to further compromise the target system.
Libreoffice version 5.4.4 and prior
Libreoffice version 6.0.0
Libreoffice version 6.0.0 alpha1
Libreoffice version 6.0.0 beta1
Libreoffice version 6.0.0 beta2
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.