The Customize WordPress Emails and Alerts WordPress plugin before 1.8.7 does not have authorisation and CSRF check in its bnfw_search_users AJAX action, allowing any authenticated users to call it and query for user e-mail prefixes (finding the first letter, then the second one, then the third one etc.).
Severity
CVSS 3.1
4.3 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS
0.4% chance of exploitation in the next 30 days; higher than 37% of CVEs (scores of 2026-10-31)