CVE-2026-1399 is a stored Cross-Site Scripting vulnerability in the WP Google Ad Manager Plugin for WordPress, affecting all versions up to and including 1.1.0. The vulnerability arises from improper neutralization of input during web page generation, allowing authenticated administrators in multi-site or restricted HTML environments to inject malicious scripts via the admin settings interface. These scripts execute in the context of users visiting the injected pages, potentially leading to limited confidentiality and integrity impacts. The vulnerability requires high privileges and no user interaction, with network attack vector and scope change.

An authenticated attacker with administrator-level permissions can inject malicious scripts that execute in the context of users accessing the affected pages. This can lead to limited confidentiality and integrity impacts, such as session hijacking or unauthorized actions performed on behalf of users. The vulnerability does not affect availability and requires high privileges, limiting the scope of potential exploitation. It specifically impacts multi-site WordPress installations or those with unfiltered_html disabled.

No official patch or fix is currently available for this vulnerability. Users should monitor the vendor's advisory for updates regarding remediation. Until a fix is released, restrict administrator access to trusted users only and consider limiting multi-site usage or configurations where unfiltered_html is disabled if possible. Review and sanitize admin input manually where feasible to reduce risk.