Execution time for an unsuccessful login differs when using a non-existing username compared to using an existing one.
Exploitability
AV:AAC:HAT:NPR:NUI:NVulnerable System
VC:LVI:NVA:NSubsequent System
SC:NSI:NSA:N2.3/CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NOther