This indicates an attack attempt to exploit an Information Disclosure Vulnerability in Atlassian Confluence Server.
A remote attacker with Add Page space permission can exploit this vulnerability by sending crafted requests to the target server. Successful exploitation could result in local file disclosure.
Atlassian Confluence Server prior to 6.13.7
Atlassian Confluence Server prior to 6.15.8
Atlassian Confluence Server prior to 6.6.16
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor.