CVE-2023-5383 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the Funnelforms Free WordPress plugin, specifically versions up to and including 3.4. The vulnerability arises from missing or incorrect nonce validation in the fnsf_copy_posts function. Nonces in WordPress are security tokens used to verify that requests originate from legitimate users and not from forged sources. Due to the lack of proper nonce validation, an unauthenticated attacker can craft a malicious request that, when executed by an authenticated site administrator (for example, by clicking a malicious link), causes the site to create copies of arbitrary posts without the administrator's explicit consent. This attack vector exploits the trust relationship between the administrator's browser and the WordPress site. The vulnerability does not require the attacker to have any privileges on the site, but it does require user interaction from an administrator, making it a UI (user interaction) dependent attack. The CVSS 3.1 base score is 4.3, indicating a medium severity level, with the attack vector being network-based, low attack complexity, no privileges required, user interaction required, and limited impact confined to integrity (creation of unauthorized post copies) without affecting confidentiality or availability. No known exploits are reported in the wild as of the publication date, and no patches have been linked yet. The vulnerability is categorized under CWE-352, which is a common weakness related to CSRF attacks.

For European organizations using WordPress websites with the Funnelforms Free plugin, this vulnerability could lead to unauthorized content duplication or manipulation. Although the impact on confidentiality and availability is minimal, the integrity of website content can be compromised, potentially leading to misinformation, defacement, or unauthorized content propagation. This could damage the organization's reputation, especially for businesses relying on their web presence for customer engagement or e-commerce. Additionally, attackers could leverage this vulnerability as a foothold for further attacks, such as injecting malicious content or phishing pages disguised as legitimate posts. The requirement for administrator interaction reduces the likelihood of widespread automated exploitation but does not eliminate risk, particularly in environments where administrators might be targeted with phishing campaigns. Given the widespread use of WordPress in Europe, especially among SMEs and public sector websites, the vulnerability poses a tangible risk to the integrity of web content and trustworthiness of affected sites.

European organizations should immediately audit their WordPress installations to identify the presence of the Funnelforms Free plugin, particularly versions up to 3.4. Until an official patch is released, administrators should consider disabling or removing the plugin to eliminate exposure. Additionally, organizations should implement strict administrative browsing policies, including the use of browser extensions or security solutions that block CSRF attacks or untrusted cross-site requests. Training administrators to recognize and avoid clicking suspicious links is critical to mitigating the user interaction requirement of this attack. Employing Web Application Firewalls (WAFs) with custom rules to detect and block suspicious POST requests targeting the fnsf_copy_posts function can provide an additional layer of defense. Monitoring logs for unusual post duplication activities can help detect exploitation attempts early. Finally, organizations should subscribe to vulnerability advisories from WordPress and plugin vendors to apply patches promptly once available.