The Cryptocurrency Prijsvergelijking Widget plugin for WordPress version 1.0 contains a stored cross-site scripting vulnerability (CWE-79) due to improper output escaping in the as_get_coin_shortcode() function. Specifically, the 'width' and 'height' shortcode attributes are rendered directly into an iframe's style attribute without escaping, allowing an attacker to prematurely terminate the style attribute and inject arbitrary HTML attributes and scripts. This can be exploited by authenticated users with contributor-level privileges or higher to inject malicious scripts that execute in the context of any user viewing the compromised page. The vulnerability 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), reflecting network attack vector, low attack complexity, required privileges, no user interaction, and partial impact on confidentiality and integrity. No official fix or patch has been identified, and no known exploits have been reported.

An attacker with contributor-level or higher access can inject arbitrary JavaScript into pages using the vulnerable shortcode, leading to stored cross-site scripting. This can result in partial confidentiality and integrity impacts, such as session hijacking or content manipulation, when other users access the infected pages. There is no impact on availability. The vulnerability affects the integrity and confidentiality of users interacting with the affected WordPress site.

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 vulnerable plugin to prevent exploitation.