The Custom Banners plugin for WordPress suffers from a reflected XSS vulnerability due to the use of add_query_arg without proper escaping of URL parameters. This flaw exists in all versions up to and including 3.3. An attacker can exploit this by crafting a malicious URL that, when visited by a user, executes arbitrary JavaScript in the context of the affected site. The vulnerability requires user interaction (clicking a link) and does not require authentication. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N, reflecting network attack vector, low attack complexity, no privileges required, user interaction required, scope changed, and low impact on confidentiality and integrity, with no impact on availability.

Successful exploitation allows an attacker to execute arbitrary scripts in the context of the vulnerable website, potentially leading to theft of user credentials, session hijacking, or other malicious actions affecting users who interact with the crafted link. The vulnerability affects confidentiality and integrity but does not impact availability. No known exploits are reported in the wild at this time.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should avoid clicking on suspicious links related to the affected plugin and consider disabling or replacing the Custom Banners plugin if feasible. Monitor official channels from the vendor ghuger for updates and patches.