register.php in Ultimate PHP Board (UPB) 1.0 and 1.0b uses an administrative account Admin with a capital "A," but allows a remote attacker to impersonate the administrator by registering an account name of admin with a lower case "a."
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
2.4% chance of exploitation in the next 30 days; higher than 83% of CVEs (scores of 2026-10-31)