CVE-2025-13898 is a stored cross-site scripting vulnerability in the Ultra Skype Button WordPress plugin by sozan45. The issue exists in all versions up to and including 1.0, where the 'btn_id' parameter of the [ultra_skype] shortcode is not properly sanitized or escaped. This allows authenticated users with Contributor or higher privileges to inject arbitrary web 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, reflecting network attack vector, low attack complexity, required privileges at the contributor level, no user interaction, and impacts confidentiality and integrity with no availability impact. No patch or vendor advisory is currently provided, and no exploits are known in the wild.

An attacker with Contributor-level or higher access can inject persistent malicious scripts into pages using the vulnerable shortcode parameter. This can lead to unauthorized script execution in the browsers of users who visit the infected pages, potentially compromising user data confidentiality and integrity. The vulnerability does not affect availability. 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 Ultra Skype Button plugin if it is not essential. Monitor for updates from the vendor or security community regarding patches or mitigations.