The MetForm plugin for WordPress suffers from a stored cross-site scripting vulnerability due to improper neutralization of input during web page generation. Specifically, the mf-template DOM element does not properly sanitize or escape input, allowing authenticated users with Contributor or higher privileges to inject malicious scripts. These scripts execute in the context of any user who accesses the compromised page, potentially leading to information disclosure or session hijacking. The vulnerability affects all versions up to 4.0.1 and has a CVSS 3.1 base score of 6.4 (AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N). No patch or official fix has been documented in the provided data.

An attacker with Contributor-level or higher access can inject persistent malicious scripts into pages via the mf-template DOM element. These scripts execute in the browsers of users who visit the infected pages, potentially leading to limited confidentiality and integrity impacts such as theft of user data or session tokens. Availability is not affected. The vulnerability requires authentication and low attack complexity but can affect all users viewing the injected content due to its stored nature.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, limit Contributor-level access to trusted users only and consider monitoring or restricting the use of the mf-template element in forms. Applying strict input validation and output escaping at the application level may reduce risk, but official remediation should be prioritized once available.