The ShareOpenly WordPress plugin prior to version 1.2.1 contains a Cross-Site Scripting vulnerability caused by the absence of WordPress's `esc_url()` escaping function on the `$url` variable before it is rendered into HTML content

Overview

The ShareOpenly WordPress plugin prior to version 1.2.1 contains a Cross-Site Scripting vulnerability caused by the absence of WordPress's esc_url() escaping function on the $url variable before it is rendered into HTML content. This variable is constructed from home_url( add_query_arg( array(), $wp->request ) ) and is concatenated directly into an HTML href attribute on every singular post or page where the plugin's sharing link is displayed. WordPress's security handbook mandates that every URL placed in HTML output must be passed through esc_url(), which both HTML-encodes special characters (converting ", <, > into their safe HTML entity equivalents) and strips dangerous URI schemes such as javascript: and data:. The omission of this function means that if the $url value ever contains HTML-special characters or a dangerous URI scheme — through a home_url WordPress filter applied by another plugin or theme, through certain web server or hosting configurations, or through future code changes — the unescaped content will be injected verbatim into the rendered HTML of every post or page on the site. Version 1.2.1 contains a patch for the issue.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.