Summary
The server is leaking information through the X-ChromeLogger-Data (or X-ChromePhp-Data) response header. The content of such headers can be customized by the developer, however it is not uncommon to find: server file system locations, vhost declarations, etc.
Solution
Disable this functionality in Production when it might leak information that could be leveraged by an attacker. Alternatively ensure that use of the functionality is tied to a strong authorization check and only available to administrators or support personnel for troubleshooting purposes not general users.
Other Info
The following represents an attempt to base64 decode the value: {"version":"4.0","columns":["label","log","backtrace","type"],"rows":[["request","Matched route \"app_security_login\" (parameters: \"_controller\": \"BackEnd\\AppBundle\\Controller\\SecurityController::loginAction\", \"_route\": \"app_security_login\")","unknown","info"],["security","Populated SecurityContext with an anonymous Token","unknown","info"]],"request_uri":"\/login"}
References
Code
org/zaproxy/zap/extension/pscanrules/XChromeLoggerDataInfoLeakScanRule.java