The Newsletters WordPress plugin before 4.18.1 does not perform an ownership check on some of its subscriber management actions, and issues a management session to unauthenticated visitors on request, allowing attackers to read any subscriber's personal data and overwrite any subscriber's record including their email address.
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Tribulant Newsletters allows Reflected XSS.This issue affects Newsletters: from n/a through 4.9.8.