CVE-2023-2964 is a stored Cross-Site Scripting (XSS) vulnerability identified in the Simple Iframe WordPress plugin versions prior to 1.2.0. The vulnerability arises because the plugin fails to properly validate the content of one of its WordPress block attributes. This improper validation allows users with at least contributor-level privileges to inject malicious scripts that are stored persistently within the plugin's data. When other users view the affected content, the malicious scripts execute in their browsers, potentially leading to session hijacking, defacement, or unauthorized actions performed on behalf of the victim. The vulnerability is classified under CWE-79, which pertains to improper neutralization of input during web page generation. The CVSS v3.1 base score is 5.4 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), privileges required (PR:L), user interaction required (UI:R), scope changed (S:C), and low impact on confidentiality and integrity (C:L/I:L) but no impact on availability (A:N). No known exploits have been reported in the wild as of the publication date. The vulnerability affects the Simple Iframe plugin, which is used to embed iframes within WordPress sites, but the vendor is unknown, and no patch links are currently available. The vulnerability was reserved on May 29, 2023, and published on July 10, 2023.

For European organizations using WordPress sites with the Simple Iframe plugin prior to version 1.2.0, this vulnerability poses a moderate risk. Since contributors can exploit the vulnerability, any user with content creation privileges can inject malicious scripts, potentially compromising other users including administrators and site visitors. This can lead to unauthorized actions such as privilege escalation, theft of authentication tokens, or defacement of websites. The impact on confidentiality and integrity is low to moderate, but the scope is significant because the vulnerability allows scope change, meaning the attack can affect components beyond the initially compromised user context. Given that WordPress is widely used across Europe for corporate, governmental, and personal websites, exploitation could undermine trust and disrupt operations, especially for organizations relying on user-generated content workflows. However, the absence of known exploits and the requirement for user interaction reduce the immediacy of the threat. Nevertheless, targeted attacks against high-value European entities with contributor-level users could leverage this vulnerability for persistent XSS attacks.

European organizations should immediately audit their WordPress installations to identify the presence of the Simple Iframe plugin and verify its version. If the plugin is installed and is a version prior to 1.2.0, organizations should restrict contributor-level permissions temporarily to trusted users only until an official patch or update is available. As no patch links are currently provided, organizations can implement web application firewall (WAF) rules to detect and block suspicious script injections in iframe block attributes. Additionally, applying Content Security Policy (CSP) headers that restrict inline script execution and limit iframe sources can mitigate the impact of stored XSS. Regularly monitoring logs for unusual contributor activity and educating contributors about safe content practices can further reduce risk. Organizations should subscribe to vendor and security mailing lists for updates on patches or mitigations. Finally, consider isolating or sandboxing iframe content to limit script execution privileges.