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.
Attack Parameters
Impact Assessment
CVSS Vector v4.0