The vulnerability identified as CVE-2025-9762 affects the 'Post By Email' plugin for WordPress developed by westi, specifically versions up to and including 1.0.4b. The root cause is the absence of proper file type validation within the save_attachments function, which processes email attachments sent to the WordPress site. This improper neutralization of special elements (CWE-78) enables unauthenticated attackers to upload arbitrary files to the server hosting the WordPress site. Since the uploaded files can be crafted to include executable code, this vulnerability can lead to remote code execution (RCE), allowing attackers to execute arbitrary commands on the server. The vulnerability is remotely exploitable over the network without any authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact on confidentiality, integrity, and availability is high, as attackers can potentially take full control of the affected system. Although no public exploits have been reported yet, the critical severity and ease of exploitation make it a high-priority threat. The lack of patch links suggests that a fix is not yet publicly available, increasing the urgency for mitigation through alternative controls. This vulnerability is particularly concerning for WordPress sites that accept posts via email and use this plugin, as it expands the attack surface to email-based inputs. Attackers could leverage this to compromise websites, steal data, deface content, or use the server as a pivot point for further attacks.

For European organizations, the impact of CVE-2025-9762 can be severe. Many businesses, government agencies, and media outlets in Europe rely on WordPress for their web presence, and some use the 'Post By Email' plugin to facilitate content publishing workflows. Successful exploitation could lead to full server compromise, resulting in data breaches, defacement, service disruption, and potential lateral movement within internal networks. This could damage organizational reputation, lead to regulatory penalties under GDPR due to data loss or exposure, and cause operational downtime. Public-facing WordPress sites are especially vulnerable, and the ability to exploit this without authentication increases the risk of widespread automated attacks. Additionally, attackers could use compromised servers to launch further attacks against European infrastructure or as part of botnets. The absence of a patch at the time of disclosure means organizations must rely on compensating controls, increasing the operational burden. The critical nature of this vulnerability demands immediate attention to prevent exploitation and mitigate potential damage.

1. Immediately disable or uninstall the 'Post By Email' plugin (westi) from all WordPress installations until a patch is available. 2. Implement strict file upload restrictions at the web server or application firewall level to block unauthorized file types and limit upload locations. 3. Monitor web server logs and WordPress logs for unusual file upload activity or unexpected email posts. 4. Employ Web Application Firewalls (WAFs) with custom rules to detect and block attempts to exploit this vulnerability, focusing on the save_attachments function behavior. 5. Restrict email sources allowed to post content via email to trusted addresses only, reducing exposure. 6. Keep WordPress core and all plugins updated regularly and subscribe to vendor security advisories for timely patching. 7. Conduct regular security audits and vulnerability scans targeting WordPress plugins to identify similar risks. 8. Consider isolating WordPress instances with this plugin in segmented network zones to limit potential lateral movement. 9. Prepare incident response plans specifically for web server compromises involving WordPress. 10. Once a patch is released, prioritize immediate testing and deployment to restore secure functionality.