CVE-2025-13543 is a vulnerability classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) found in the PostGallery plugin for WordPress, developed by rtowebsites. The vulnerability arises from inadequate validation of file types in the PostGalleryUploader class functions, allowing authenticated users with subscriber-level permissions or higher to upload arbitrary files to the server. Since WordPress subscriber roles typically have limited capabilities, this vulnerability is notable because it escalates the risk from relatively low-privilege users. The uploaded files can be crafted to include malicious code, potentially enabling remote code execution (RCE) on the web server hosting the WordPress site. The CVSS 3.1 score of 8.8 reflects the vulnerability's network attack vector (AV:N), low attack complexity (AC:L), required privileges (PR:L), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). This means an attacker can exploit the vulnerability remotely with minimal effort once authenticated, leading to full compromise of the affected system. The vulnerability affects all versions of PostGallery up to and including 1.12.5, with no patch currently available at the time of disclosure. No known exploits have been observed in the wild yet, but the potential for exploitation is significant given the widespread use of WordPress and the common presence of subscriber-level accounts. The vulnerability's root cause is the failure to properly restrict file types during upload, which is a common security oversight in web applications that handle user-generated content.

For European organizations, this vulnerability poses a serious threat to websites running WordPress with the PostGallery plugin installed. Successful exploitation can lead to remote code execution, allowing attackers to execute arbitrary commands on the server, steal sensitive data, deface websites, or use the compromised server as a pivot point for further network attacks. This can result in data breaches, service outages, reputational damage, and potential regulatory penalties under GDPR if personal data is exposed. Organizations with subscriber-level user roles enabled on their WordPress sites are particularly vulnerable, as attackers do not need administrative privileges to exploit the flaw. The impact extends to any sector relying on WordPress for web presence, including e-commerce, government portals, educational institutions, and media companies. The availability of the plugin across multiple countries and the common use of WordPress in Europe increase the risk of widespread exploitation if not promptly mitigated.

1. Monitor for and apply official patches or updates from rtowebsites for the PostGallery plugin as soon as they are released. 2. In the absence of a patch, immediately restrict file upload permissions by disabling the PostGallery plugin or limiting upload capabilities to trusted roles only. 3. Implement web application firewall (WAF) rules to detect and block suspicious file upload attempts, especially those with executable extensions or unusual payloads. 4. Enforce strict server-side file type validation and sanitization beyond the plugin's controls, including MIME type checks and file content inspection. 5. Regularly audit user roles and permissions in WordPress to minimize the number of users with upload capabilities. 6. Employ intrusion detection systems (IDS) and continuous monitoring to detect anomalous activities indicative of exploitation attempts. 7. Backup website data and configurations frequently to enable rapid recovery in case of compromise. 8. Educate site administrators about the risks of arbitrary file uploads and the importance of timely updates.