XMLRPC Attacks Blocker, versions 1.0 and earlier, improperly trusts the X‑Forwarded‑For HTTP header and logs the value without sanitization. When an administrator opens the debug log page, the unescaped header content is rendered as part of the page, allowing an unauthenticated attacker to insert arbitrary JavaScript. This stored cross‑site scripting grants the attacker the ability to execute code in the admin context, potentially hijacking sessions, defacing content, or exfiltrating data.

Vulnerability applies to the Yehudah xmlrpc attacks blocker plugin for WordPress, up to and including version 1.0. Sites that have the plugin installed and enabled its debug logging feature are affected; other WordPress plugins or CMS versions are not impacted.

The CVSS score of 6.1 represents a moderate severity, while the EPSS score of less than 1 % indicates that exploitation is currently infrequent. The vulnerability is not present in the CISA KEV catalog. Exploitation requires only that an attacker point a request with a crafted X‑Forwarded‑For header at the vulnerable site; no authentication is necessary, and the malicious script executes with the privileges of any administrator who views the debug log. Organizations should treat this as a priority for remediation.