CVE-2026-108566A vulnerability has been found in InstantSoft icms2 up to 2.18.2. This issue affects the function index of the file templates/default/controllers/messages/index.tpl.php of the component Private Message Handler. Such manipulation of the argument nickname leads to cross site scripting. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The name of the patch is 3a1ec8fcb073a46d06a2ab83bc2bf68225834281. It is best practice to apply a patch to resolve this issue.