CVE-2023-6139 is a vulnerability identified in the Essential Real Estate WordPress plugin versions prior to 4.4.0. The core issue is a missing authorization check (CWE-862) on AJAX actions within the plugin. Specifically, the plugin fails to properly verify user capabilities before processing certain AJAX requests. This flaw allows attackers who have subscriber-level access—typically the lowest privilege level in WordPress—to exploit these AJAX endpoints without proper permission validation. The primary impact of this vulnerability is the ability for such low-privileged users to conduct Denial of Service (DoS) attacks against the affected WordPress site. The vulnerability does not affect confidentiality or integrity directly, but it can severely impact availability by overwhelming server resources or triggering resource-intensive operations via the AJAX endpoints. The CVSS v3.1 score is 6.5 (medium severity), reflecting the network attack vector (remote exploitation), low attack complexity, and the requirement for low privileges but no user interaction. No known exploits are currently reported in the wild, and no patches are explicitly linked, though upgrading to version 4.4.0 or later is implied to resolve the issue. The vulnerability is significant because WordPress is widely used, and Essential Real Estate is a niche but potentially widely deployed plugin for real estate websites, which may be critical for business operations.

For European organizations, especially those operating real estate websites or portals using WordPress with the Essential Real Estate plugin, this vulnerability poses a risk to service availability. A successful DoS attack could disrupt website functionality, leading to downtime, loss of customer trust, and potential revenue loss. Given that real estate platforms often serve as critical business tools for property listings and client interactions, unavailability could impact business continuity. Additionally, organizations subject to regulatory requirements around service availability and incident response (such as GDPR mandates on operational resilience) may face compliance risks if the vulnerability is exploited. The fact that exploitation requires only subscriber-level access means that even minimally privileged users or compromised low-level accounts could trigger attacks, increasing the threat surface. While no direct data breach risk is indicated, the disruption potential is non-trivial, particularly for SMEs and agencies relying heavily on their online presence.

1. Immediate upgrade of the Essential Real Estate plugin to version 4.4.0 or later where the authorization checks are properly implemented. 2. Review and restrict subscriber-level user registrations and permissions to minimize the risk of malicious actors gaining low-level access. 3. Implement Web Application Firewall (WAF) rules to detect and block abnormal AJAX request patterns targeting the plugin’s endpoints. 4. Monitor server resource usage and logs for unusual spikes or repeated AJAX calls that could indicate exploitation attempts. 5. Consider disabling or limiting AJAX functionalities of the plugin if not essential, until a patch is applied. 6. Conduct regular security audits of all WordPress plugins to ensure timely patching and proper access controls. 7. Employ rate limiting on AJAX endpoints to reduce the risk of DoS attacks originating from authenticated users.