CVE-2026-1099 is a stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, found in the Administrative Shortcodes WordPress plugin developed by shazdeh. The flaw exists in all plugin versions up to and including 0.3.4, where the 'login' and 'logout' shortcode attributes do not properly sanitize or escape user-supplied input before rendering it on web pages. This improper neutralization allows authenticated users with Contributor-level permissions or higher to embed arbitrary JavaScript code into pages. When other users access these pages, the malicious scripts execute in their browsers, potentially leading to session hijacking, theft of cookies, or unauthorized actions performed with the victim's privileges. The vulnerability is exploitable remotely over the network without user interaction but requires the attacker to have at least Contributor-level access, which is a moderate barrier. The CVSS 3.1 base score is 6.4, reflecting a medium severity with low attack complexity and partial impact on confidentiality and integrity but no impact on availability. No public exploits have been reported yet, but the vulnerability poses a risk to WordPress sites using this plugin, especially those with multiple authenticated users. The absence of official patches at the time of disclosure necessitates immediate mitigation steps to prevent exploitation.

For European organizations, this vulnerability can lead to unauthorized script execution within trusted WordPress environments, compromising user sessions and potentially enabling privilege escalation attacks. This can result in data leakage, unauthorized access to sensitive information, and manipulation of website content or functionality. Organizations relying on WordPress for public-facing websites, intranets, or customer portals are at risk of reputational damage and regulatory non-compliance if personal data is exposed. The requirement for Contributor-level access limits the attack surface but does not eliminate risk, especially in environments with multiple content editors or contributors. The vulnerability could be leveraged in targeted attacks against organizations with valuable web assets or high-profile user bases. Given the widespread use of WordPress across Europe, the impact could be significant if exploited at scale.

European organizations should immediately audit their WordPress installations to identify the presence of the Administrative Shortcodes plugin and verify its version. Until an official patch is released, restrict Contributor-level and higher permissions to trusted users only, minimizing the risk of malicious shortcode injection. Implement Web Application Firewall (WAF) rules to detect and block suspicious shortcode attribute patterns or script tags in user inputs. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts on affected sites. Regularly monitor logs for unusual shortcode usage or unexpected page content changes. Educate content contributors about the risks of injecting untrusted content. Once a patch becomes available, prioritize timely updates. Additionally, consider disabling or removing the plugin if it is not essential to reduce attack surface.