The Envo Extra plugin for WordPress suffers from a stored XSS vulnerability via the 'button_css_id' parameter in the Button widget due to improper input neutralization. This allows authenticated users with Contributor or higher privileges to inject arbitrary JavaScript that executes in the context of other users viewing the injected pages. The vulnerability affects all versions up to and including 1.8.23. The CVSS 3.1 base score is 6.4, reflecting network attack vector, low attack complexity, privileges required at the contributor level, no user interaction needed, and impacts on confidentiality and integrity with no availability impact. No patch or remediation details are provided in the available data.

Successful exploitation allows an authenticated attacker with Contributor-level or higher privileges to inject persistent malicious scripts into pages via the 'button_css_id' parameter. These scripts execute in the browsers of users who visit the compromised pages, potentially leading to unauthorized actions or data disclosure within the context of the affected site. The impact is limited to confidentiality and integrity with no direct availability impact. There are no known active exploits reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, restrict Contributor-level access to trusted users only and consider disabling or removing the Envo Extra plugin if feasible. Monitor vendor channels for updates and apply patches promptly once available.