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 flaw exists in the PostGalleryUploader class, where file type validation is insufficient or improperly implemented, allowing authenticated users with subscriber-level permissions or higher to upload arbitrary files to the server. Since WordPress subscriber roles typically have limited capabilities, the vulnerability is notable because it escalates the impact of a low-privilege user. Uploaded files can include malicious scripts or web shells, potentially enabling remote code execution (RCE) on the hosting server. The vulnerability affects all versions up to and including 1.12.5, with no patch currently available at the time of disclosure. The CVSS v3.1 score is 8.8 (high), reflecting network attack vector, low attack complexity, required privileges at the low level, no user interaction, and high impact on confidentiality, integrity, and availability. Although no known exploits are publicly reported, the vulnerability poses a significant risk due to the widespread use of WordPress and the common deployment of the PostGallery plugin. Attackers could leverage this to gain persistent access, deface websites, steal data, or pivot within the network.

For European organizations, this vulnerability presents a substantial risk to web infrastructure security. Organizations relying on WordPress with the PostGallery plugin are exposed to potential remote code execution attacks, which could lead to data breaches, website defacement, service disruption, or full server compromise. Given the ease of exploitation by authenticated users with minimal privileges, insider threats or compromised low-level accounts could be leveraged by attackers. The impact extends to confidentiality (exfiltration of sensitive data), integrity (alteration of website content or data), and availability (denial of service through server compromise). This is particularly critical for sectors with strict data protection regulations such as finance, healthcare, and government entities in Europe. The absence of a patch at disclosure increases the window of exposure, emphasizing the need for immediate mitigation. The threat also poses reputational risks and potential regulatory penalties under GDPR if personal data is compromised.

Immediate mitigation steps include restricting user roles and permissions to minimize the number of users with upload capabilities. Administrators should disable or limit the use of the PostGallery plugin until a security patch is released. Implementing web application firewalls (WAF) with rules to detect and block suspicious file uploads can reduce risk. Monitoring upload directories for unauthorized or unusual file types and scanning uploaded files for malware is recommended. Employing strict server-side validation for file types and extensions, and disabling execution permissions on upload directories, can prevent execution of malicious files. Regularly auditing user accounts and enforcing strong authentication mechanisms will reduce the risk of compromised credentials. Once available, promptly apply vendor patches or updates. Additionally, organizations should maintain comprehensive backups and incident response plans to recover quickly from potential exploitation.