CVE-2025-9632 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the PhpList Subber plugin for WordPress, developed by vinzzb. This vulnerability exists in all versions up to and including 1.1 due to missing or incorrect nonce validation in the bulk_action_handler function. Nonces in WordPress are security tokens used to verify that requests originate from legitimate users and not from malicious third parties. The absence or improper implementation of nonce validation allows an attacker to craft a malicious request that, when executed by an authenticated site administrator (e.g., by clicking a link), triggers unauthorized bulk synchronization of subscription forms. This action could lead to unintended modifications or disruptions in subscription data management. The vulnerability does not require the attacker to be authenticated but does require user interaction from an administrator, such as clicking a specially crafted link. The CVSS v3.1 base score is 4.3 (medium severity), reflecting that the attack vector is network-based, with low attack complexity, no privileges required, but requiring user interaction. The impact affects integrity but not confidentiality or availability. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability is categorized under CWE-352, which specifically relates to CSRF attacks that exploit the trust a web application has in the user's browser.

For European organizations using WordPress sites with the PhpList Subber plugin, this vulnerability could allow attackers to manipulate subscription form synchronization processes without authorization. While the confidentiality and availability of systems are not directly impacted, the integrity of subscription data could be compromised, potentially leading to incorrect subscription lists, unauthorized subscription changes, or disruption in communication workflows. This could affect marketing campaigns, customer communications, or internal notifications relying on subscription data. Organizations in sectors with strict data integrity requirements, such as finance, healthcare, or government, may face reputational damage or compliance issues if subscription data is altered maliciously. Since exploitation requires an administrator to interact with a malicious link, targeted phishing or social engineering campaigns could be used to trigger the attack, increasing risk in environments where administrators have elevated privileges and are less cautious with links. The medium severity rating indicates moderate risk, but the potential for indirect impacts on business processes and trustworthiness of communications should not be underestimated.

To mitigate this vulnerability, organizations should immediately verify if their WordPress installations use the PhpList Subber plugin and identify the version in use. Since no official patch links are currently available, administrators should consider temporarily disabling the plugin or restricting access to the bulk synchronization functionality to trusted users only. Implementing web application firewalls (WAFs) with custom rules to detect and block suspicious bulk_action_handler requests can reduce risk. Administrators should be trained to recognize phishing attempts and avoid clicking on untrusted links, especially when logged into administrative accounts. Monitoring logs for unusual bulk synchronization activities can help detect exploitation attempts. Developers or site maintainers should apply nonce validation correctly in the bulk_action_handler function as soon as a patch is released. Additionally, applying the principle of least privilege by limiting administrator access and using multi-factor authentication (MFA) can reduce the likelihood of successful exploitation.