CVE-2022-3831 is a medium-severity Stored Cross-Site Scripting (XSS) vulnerability identified in the reCAPTCHA WordPress plugin, specifically affecting versions up to 1.6. The vulnerability arises because the plugin fails to properly sanitize and escape certain settings inputs. This flaw allows users with high privileges, such as administrators, to inject malicious scripts that are stored persistently within the plugin's settings. Notably, this exploit can be executed even when the WordPress capability 'unfiltered_html' is disabled, which is a common restriction in multisite WordPress environments to prevent unauthorized HTML/script insertion. The vulnerability requires high privilege (admin) access and user interaction (i.e., the admin must perform some action to trigger the stored XSS). The attack vector is network-based with low attack complexity, and the scope is changed, meaning the vulnerability can affect resources beyond the initially vulnerable component. The impact on confidentiality and integrity is low, with no direct impact on availability. The vulnerability could allow an attacker to execute arbitrary JavaScript in the context of the affected site, potentially leading to session hijacking, privilege escalation, or further compromise of the WordPress environment if exploited. However, exploitation requires the attacker to already have administrative access, limiting the initial attack surface. There are no known exploits in the wild as of the publication date, and no official patches have been linked yet. The vulnerability is tracked under CWE-79, which corresponds to Cross-Site Scripting issues caused by improper input validation and output encoding.

For European organizations using WordPress sites with the affected reCAPTCHA plugin, this vulnerability poses a risk primarily to site integrity and confidentiality. Since exploitation requires administrative privileges, the main concern is insider threats or attackers who have already compromised admin credentials. Successful exploitation could allow attackers to inject malicious scripts that execute in the browsers of other administrators or users with elevated privileges, potentially leading to session hijacking, theft of sensitive data, or further compromise of site controls. In multisite WordPress setups, which are common in large organizations and educational institutions across Europe, the risk is amplified because the vulnerability bypasses the 'unfiltered_html' restriction, potentially affecting multiple sites within the network. Although the CVSS score is medium (4.8), the scoped impact and the ability to escalate privileges or maintain persistence make it a significant concern for organizations that rely heavily on WordPress for public-facing or internal portals. The lack of known exploits reduces immediate risk, but the presence of this vulnerability in a widely used plugin means that European organizations should prioritize mitigation to prevent potential targeted attacks, especially in sectors like government, education, and media where WordPress multisite deployments are prevalent.

Immediately audit WordPress installations to identify the presence of the reCAPTCHA plugin version 1.6 or earlier. Restrict administrative access strictly to trusted personnel and enforce strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise. Implement strict role-based access controls (RBAC) to minimize the number of users with high privileges capable of exploiting this vulnerability. Monitor and review plugin settings and configurations regularly for unauthorized or suspicious changes that could indicate exploitation attempts. Apply manual sanitization and escaping of plugin settings if possible, or temporarily disable the plugin until an official patch is released. Use Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting plugin settings inputs. Educate administrators on the risks of stored XSS and the importance of cautious input handling within WordPress admin interfaces. Track updates from the plugin vendor or WordPress security advisories for patches addressing this vulnerability and apply them promptly once available.