CVE-2022-4004 is a security vulnerability identified in the Donation Button WordPress plugin, affecting versions up to and including 4.0.0. The core issue is a missing authorization check (CWE-862) in the AJAX action handler named "donation_button_twilio_send_test_sms." This flaw allows any authenticated user with an account on the affected WordPress site, including low-privileged roles such as subscribers, to invoke the plugin's Twilio SMS sending functionality without proper privilege verification or nonce token validation. Consequently, these users can send SMS messages to arbitrary phone numbers using the site's Twilio integration. The vulnerability does not require user interaction beyond having an authenticated account, and it can be exploited remotely over the network (AV:N). The CVSS v3.1 base score is 4.3 (medium severity), reflecting low complexity (AC:L), requiring low privileges (PR:L), no user interaction (UI:N), and no impact on confidentiality or availability, but with limited integrity impact (I:L). No known exploits have been reported in the wild, and no official patches or updates have been linked in the provided data. The vulnerability arises from improper authorization checks in the plugin's AJAX endpoint, which should have validated user permissions and nonce tokens to prevent unauthorized use of the SMS sending feature. This flaw could be leveraged to send unsolicited SMS messages, potentially leading to abuse such as spam, phishing, or reputational damage to the affected site owners.

For European organizations using the Donation Button WordPress plugin, this vulnerability poses a risk primarily related to misuse of the SMS sending capability integrated via Twilio. Attackers with low-level access could send unauthorized SMS messages, which may lead to financial costs due to SMS charges, reputational harm if the messages are used for spam or phishing campaigns, and potential regulatory scrutiny under GDPR if personal data is mishandled or if the abuse leads to data breaches. Although the vulnerability does not directly compromise confidentiality or availability, the integrity of the messaging function is impacted, and the organization's trustworthiness could be undermined. Organizations relying on WordPress sites with this plugin, especially those in sectors with high customer interaction or regulatory oversight (e.g., finance, healthcare, public services), may face increased risk. The ability for low-privileged users to abuse the SMS function could also facilitate social engineering attacks against customers or employees. However, since exploitation requires an authenticated account, the threat is limited to insiders or users who have registered on the site, reducing the attack surface compared to unauthenticated remote exploits.

European organizations should immediately audit their WordPress installations to identify the presence of the Donation Button plugin and verify the version in use. Since no official patch links are provided, administrators should consider the following specific mitigations: 1) Disable or remove the Donation Button plugin if it is not essential to reduce attack surface. 2) Restrict user registration or enforce stricter user role assignments to prevent untrusted users from gaining accounts capable of exploiting this vulnerability. 3) Implement Web Application Firewall (WAF) rules to monitor and block unauthorized AJAX requests to the "donation_button_twilio_send_test_sms" endpoint, especially those originating from low-privileged accounts. 4) If feasible, modify the plugin code to add proper authorization checks and nonce validation in the AJAX handler as an interim fix. 5) Monitor Twilio account usage for unusual SMS sending patterns that could indicate exploitation. 6) Educate site administrators and users about the risk and encourage prompt reporting of suspicious activity. 7) Stay alert for official patches or updates from the plugin vendor or WordPress security channels and apply them promptly once available.