CVE-2025-13065 is a vulnerability classified under CWE-434 (Unrestricted Upload of File with Dangerous Type) found in the Starter Templates plugin for WordPress, developed by Brainstormforce. The issue arises from insufficient validation of uploaded file types, specifically the plugin's failure to properly detect and block files with double extensions disguised as WXR files, which are XML-based WordPress export files. Authenticated users with at least author-level permissions can exploit this flaw to upload arbitrary files, including potentially malicious scripts, to the server hosting the WordPress site. Because the plugin accepts these files as valid WXR files, it bypasses sanitization checks. This arbitrary file upload can lead to remote code execution (RCE), allowing attackers to execute commands on the server, compromise site integrity, steal data, or disrupt availability. The vulnerability affects all versions up to and including 4.4.41 of the plugin. The CVSS v3.1 score of 8.8 reflects the vulnerability's network attack vector, low attack complexity, required privileges at the author level, no user interaction, and high impact on confidentiality, integrity, and availability. Although no known exploits are currently reported in the wild, the potential for exploitation is significant given the widespread use of WordPress and this plugin. The vulnerability was publicly disclosed on December 6, 2025, with no patch links available at the time, emphasizing the need for immediate attention by site administrators.

For European organizations, this vulnerability poses a significant risk, especially for those relying on WordPress sites with the Starter Templates plugin. Successful exploitation could lead to unauthorized access, data breaches, defacement, or full server compromise. This can disrupt business operations, damage reputation, and lead to regulatory non-compliance under GDPR due to potential data exposure. The ability to execute arbitrary code remotely increases the risk of persistent threats and lateral movement within networks. Organizations in sectors such as e-commerce, media, education, and government, which often use WordPress for public-facing websites, are particularly vulnerable. The impact is exacerbated in environments where multiple users have author-level access, increasing the attack surface. Additionally, the lack of a patch at disclosure time means organizations must rely on compensating controls to mitigate risk temporarily.

Immediate mitigation steps include restricting author-level access to trusted users only and auditing existing user privileges to minimize potential attackers. Implement web application firewalls (WAFs) with rules to detect and block suspicious file uploads, especially those with double extensions or unusual MIME types. Disable or limit file upload functionality where not necessary. Monitor server logs for unusual upload activity or execution of unexpected scripts. Employ intrusion detection systems (IDS) to identify exploitation attempts. Until an official patch is released, consider temporarily disabling the Starter Templates plugin or replacing it with alternative solutions. Once a patch becomes available, apply it promptly. Additionally, implement strict input validation and sanitization on all file uploads, and ensure that the WordPress environment and all plugins are kept up to date. Regular backups and incident response plans should be in place to recover quickly from any compromise.