The Perfmatters plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 2.6.4 via the 's' parameter. This makes it possible for unauthenticated attackers to read the contents of arbitrary files on the server, which can contain sensitive information. Exploitation requires the Local Google Fonts feature to be enabled (disabled by default), pretty permalinks to be active, and RSS feed links to remain enabled in the plugin settings.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:HI:NA:N7.5/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NInput Validation