CVE-2025-4857 is a high-severity vulnerability classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory, commonly known as Path Traversal) affecting the 'Newsletters' plugin for WordPress developed by contrid. This vulnerability exists in all versions up to and including 4.9.9.9. The flaw arises from insufficient validation of the 'file' parameter, which allows authenticated users with Administrator-level privileges or higher to perform Local File Inclusion (LFI). By exploiting this vulnerability, an attacker can include arbitrary files from the server's filesystem, potentially executing arbitrary PHP code contained within those files. This capability enables attackers to bypass access controls, access sensitive data, and achieve remote code execution (RCE) on the affected server. The vulnerability is particularly dangerous because it leverages the ability to upload files that are typically considered safe, such as images, which can then be included and executed as PHP code. The CVSS v3.1 base score is 7.2, indicating a high severity level, with an attack vector of network (remote exploitation), low attack complexity, requiring high privileges (administrator), no user interaction, and impacting confidentiality, integrity, and availability. No known exploits are currently reported in the wild, but the vulnerability's nature and impact make it a critical concern for WordPress sites using this plugin.

For European organizations, this vulnerability poses a significant risk, especially for those relying on WordPress sites with the contrid Newsletters plugin installed. Successful exploitation could lead to unauthorized disclosure of sensitive data, including personal data protected under GDPR, resulting in regulatory penalties and reputational damage. The ability to execute arbitrary code on web servers can lead to full system compromise, enabling attackers to deploy malware, ransomware, or pivot to internal networks. This is particularly impactful for organizations in sectors such as finance, healthcare, government, and e-commerce, where data confidentiality and service availability are critical. Additionally, compromised websites can be used to distribute malicious content or conduct phishing campaigns targeting European users, amplifying the threat landscape. The requirement for administrator-level access limits exploitation to insiders or attackers who have already compromised credentials, but given the prevalence of credential theft and phishing, this remains a realistic threat vector.

1. Immediate patching: Organizations should monitor for official patches or updates from contrid for the Newsletters plugin and apply them promptly once available. 2. Access control hardening: Limit administrator access strictly to trusted personnel and enforce strong authentication mechanisms, including multi-factor authentication (MFA), to reduce the risk of credential compromise. 3. Input validation and sanitization: Until a patch is available, implement web application firewall (WAF) rules to detect and block suspicious requests targeting the 'file' parameter to prevent path traversal attempts. 4. File upload restrictions: Enforce strict file type validation and scanning on uploads to prevent uploading of potentially executable files disguised as images or other safe types. 5. Monitoring and logging: Enable detailed logging of administrator actions and file access to detect anomalous behavior indicative of exploitation attempts. 6. Incident response readiness: Prepare to isolate and remediate affected systems quickly if exploitation is detected, including restoring from clean backups. 7. Plugin alternatives: Consider replacing the vulnerable plugin with alternative newsletter solutions that have a better security track record until a secure version is released.