CVE-2026-1809 is a stored cross-site scripting vulnerability classified under CWE-79, found in the HTML Tag Shortcodes plugin for WordPress developed by jhoylman. The vulnerability exists in all versions up to and including 1.1 due to improper neutralization of input during web page generation. Specifically, the plugin fails to adequately sanitize and escape user-supplied attributes in its shortcode implementation. This flaw allows authenticated users with contributor-level privileges or higher to inject arbitrary JavaScript code into pages or posts via shortcode attributes. When other users access these compromised pages, the injected scripts execute in their browsers, potentially leading to session hijacking, privilege escalation, defacement, or distribution of malware. The vulnerability has a CVSS 3.1 base score of 6.4, indicating medium severity, with an attack vector of network (remote exploitation), low attack complexity, requiring privileges (contributor or above), no user interaction, and a scope change affecting confidentiality and integrity but not availability. No public exploits have been reported yet, and no patches are currently linked, indicating that mitigation relies on administrative controls and monitoring until an official fix is released. The vulnerability is particularly concerning for multi-author WordPress sites where contributors can add content but are not fully trusted. The stored nature of the XSS means the malicious payload persists in the database and affects all users viewing the infected content.

For European organizations, this vulnerability poses a significant risk to websites running WordPress with the affected HTML Tag Shortcodes plugin. Exploitation can lead to unauthorized disclosure of user session tokens, enabling attackers to impersonate users, including administrators, thereby compromising site integrity and confidentiality. This can result in defacement, data theft, or the injection of further malicious payloads such as ransomware or phishing kits. Organizations relying on WordPress for public-facing websites, intranets, or customer portals may suffer reputational damage and regulatory consequences under GDPR if personal data is exposed. The requirement for contributor-level access limits the attack surface but does not eliminate risk, especially in environments with many content creators or weak internal controls. The vulnerability does not impact availability directly but can indirectly cause service disruptions through administrative account compromise or cleanup efforts. Since no known exploits are in the wild, the immediate risk is moderate, but the potential for future exploitation remains high if unpatched.

1. Immediately audit user roles and permissions to restrict contributor-level access only to trusted individuals. 2. Implement strict content review and approval workflows before publishing content containing shortcodes. 3. Monitor shortcode usage and database entries for suspicious or unexpected scripts or HTML tags. 4. Employ Web Application Firewalls (WAFs) with custom rules to detect and block malicious script injections targeting shortcode attributes. 5. Disable or remove the HTML Tag Shortcodes plugin if not essential, or replace it with a more secure alternative. 6. Stay alert for official patches or updates from the plugin vendor and apply them promptly once available. 7. Educate content contributors about safe content practices and the risks of injecting untrusted code. 8. Use security plugins that provide real-time scanning for XSS and other injection attacks. 9. Regularly back up website data to enable recovery in case of compromise. 10. Conduct penetration testing focused on shortcode inputs to identify and remediate similar vulnerabilities.