CVE-2024-13940 is a Server-Side Request Forgery (SSRF) vulnerability identified in the Ninja Forms Webhooks plugin for WordPress, affecting all versions up to and including 3.0.7. SSRF vulnerabilities allow an attacker to induce the server-side application to make HTTP requests to arbitrary domains or IP addresses, potentially including internal or protected network resources that are not directly accessible from the outside. In this case, the vulnerability exists in the webhook functionality of the plugin, which is designed to send HTTP requests triggered by form submissions. An attacker with Administrator-level privileges or higher on the WordPress site can exploit this flaw to craft malicious webhook requests that cause the server to send requests to arbitrary locations. This can lead to unauthorized querying or modification of internal services or resources that are otherwise inaccessible externally. The vulnerability requires high privileges (Administrator or above) and does not require user interaction beyond the attacker’s authenticated access. The CVSS 3.1 base score is 5.5 (medium severity), reflecting the network attack vector, low attack complexity, high privileges required, no user interaction, and partial impact on confidentiality and integrity but no impact on availability. The scope is changed, meaning the vulnerability affects components beyond the vulnerable plugin itself, potentially impacting other internal services. No known exploits in the wild have been reported yet, and no official patches are linked at this time. The vulnerability is classified under CWE-918, which covers SSRF issues where the server is tricked into making unintended requests. This vulnerability is significant because WordPress is widely used across many organizations, and Ninja Forms is a popular plugin for form management. The ability to make arbitrary requests from the server can be leveraged for reconnaissance of internal networks, accessing sensitive internal APIs, or manipulating internal services, potentially leading to further compromise.

For European organizations, this vulnerability poses a moderate risk primarily to those using WordPress sites with the Ninja Forms Webhooks plugin installed and active. Given that exploitation requires Administrator-level access, the initial compromise vector is likely through credential theft, phishing, or insider threat. Once exploited, attackers can pivot within internal networks by accessing internal services that are normally shielded from external access, potentially exposing sensitive data or enabling further lateral movement. This can be particularly impactful for organizations with complex internal IT infrastructures, such as financial institutions, healthcare providers, or government agencies, where internal services may contain critical or regulated information. The vulnerability could also be used to bypass network segmentation controls, undermining defense-in-depth strategies. Additionally, the integrity of internal services could be compromised if the attacker uses SSRF to send malicious requests that alter internal data or configurations. Although availability is not directly impacted, the confidentiality and integrity risks are significant enough to warrant attention. The medium severity rating suggests that while this is not an immediate critical threat, it can be a stepping stone in a multi-stage attack chain, especially in environments where internal services are highly trusted and interconnected.

1. Immediate mitigation should focus on restricting Administrator-level access to trusted personnel only and enforcing strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of credential compromise. 2. Organizations should audit their WordPress installations to identify if the Ninja Forms Webhooks plugin is installed and determine the version in use. 3. If possible, disable the webhook functionality or the plugin entirely until a patch or update is released by the vendor. 4. Implement network-level controls such as egress filtering on the web server hosting WordPress to restrict outbound HTTP requests to only trusted destinations, thereby limiting the potential for SSRF exploitation. 5. Monitor web server logs and application logs for unusual outbound requests or patterns indicative of SSRF activity. 6. Employ Web Application Firewalls (WAFs) with rules designed to detect and block SSRF attempts targeting webhook endpoints. 7. Keep WordPress core and all plugins updated regularly and subscribe to vendor security advisories for timely patching once a fix is available. 8. Conduct internal network segmentation to limit the exposure of sensitive internal services to the web server hosting WordPress. 9. Review and harden internal APIs and services to require strong authentication and authorization, reducing the impact of SSRF-induced requests. 10. Educate administrators on the risks of SSRF and the importance of safeguarding privileged accounts.