CVE-2025-9762 is a critical vulnerability identified in the 'Post By Email' plugin for WordPress, developed by westi. This vulnerability arises from improper neutralization of special elements used in OS commands (CWE-78), specifically due to a lack of file type validation in the save_attachments function across all versions up to and including 1.0.4b. The flaw allows unauthenticated attackers to upload arbitrary files to the affected WordPress site's server. Because the plugin does not restrict or validate the types of files uploaded, attackers can potentially upload malicious scripts or executables. This can lead to remote code execution (RCE), enabling attackers to execute arbitrary commands on the server with the privileges of the web server process. The vulnerability has a CVSS 3.1 base score of 9.8, indicating critical severity, with an attack vector of network (AV:N), no required privileges (PR:N), no user interaction (UI:N), and full impact on confidentiality, integrity, and availability (C:H/I:H/A:H). There are no known exploits in the wild yet, and no patches have been released at the time of publication (September 30, 2025). Given the widespread use of WordPress and the popularity of plugins that enable posting content via email, this vulnerability represents a significant risk to websites using this plugin, as attackers can compromise sites remotely without authentication or user interaction.

For European organizations, the impact of this vulnerability can be severe. Many businesses, government agencies, and non-profits in Europe rely on WordPress for their web presence, including public-facing websites and internal portals. Exploitation could lead to full server compromise, data breaches involving sensitive customer or employee information, defacement of websites, disruption of services, and potential lateral movement within internal networks. The critical nature of the vulnerability means attackers can gain control without any authentication, increasing the risk of automated mass exploitation campaigns. This could result in reputational damage, regulatory penalties under GDPR for data breaches, and operational downtime. Organizations in sectors such as finance, healthcare, and government are particularly at risk due to the sensitivity of their data and the potential impact on public trust and national security.

Immediate mitigation steps include disabling the 'Post By Email' plugin until a secure patch is released. Organizations should monitor official vendor channels and WordPress plugin repositories for updates or patches addressing this vulnerability. In the interim, applying web application firewall (WAF) rules to block suspicious file uploads or requests targeting the plugin's endpoints can reduce exposure. Conduct thorough audits of web server file systems and logs to detect any signs of unauthorized file uploads or suspicious activity. Implement strict file upload restrictions and validation at the web server or application firewall level. Additionally, ensure that the web server runs with the least privileges necessary to limit the impact of any potential compromise. Organizations should also review their incident response plans to prepare for potential exploitation and consider network segmentation to isolate web servers from critical internal systems.