This vulnerability in Intermark IT WebControl CMS v3.5 is caused by improper neutralization of input during web page generation, specifically in the contact form processing at '/processContact.do'. An attacker can exploit this by submitting malicious HTML code through the 'nombreApellidos', 'dirección ', and 'comentarios ' parameters, leading to HTML injection that may execute in the victim's browser. The CVSS 4.0 base score is 5.1, reflecting a medium severity with network attack vector, low attack complexity, no privileges required, and requiring user interaction. No official fix or patch has been documented as of the publication date.

Successful exploitation allows an attacker to inject malicious HTML content into emails sent via the contact form, potentially leading to cross-site scripting attacks against recipients. This can result in execution of arbitrary scripts in the context of the victim's browser, which may lead to session hijacking, phishing, or other malicious activities. However, the attack requires user interaction (the victim to receive and interact with the crafted email).

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should exercise caution when interacting with emails originating from the contact form of affected WebControl CMS instances. Implementing input validation and output encoding on the affected parameters may reduce risk, but official remediation should be prioritized once available.