CVE-2026-0829 is a vulnerability identified in the Frontend File Manager WordPress plugin, versions up to 23.5, that results from missing authorization controls (CWE-862) in the plugin’s frontend components. This flaw allows unauthenticated users to send emails through the WordPress site without any security verification, effectively turning the site into an open mail relay. Attackers can exploit this to distribute spam or phishing emails, potentially damaging the reputation of the affected domain and facilitating broader phishing campaigns. Furthermore, the vulnerability permits attackers to guess file IDs to access and share uploaded files without permission, exposing potentially sensitive or confidential information stored on the site. The vulnerability has a CVSS v3.1 base score of 5.8, reflecting medium severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and a scope change (S:C). The impact primarily affects integrity (unauthorized email sending) and confidentiality (unauthorized file access), with no direct impact on availability. No patches or known exploits have been reported at the time of publication. The vulnerability is significant because WordPress powers a large portion of the web, and plugins like Frontend File Manager are commonly used for file handling and communication. Exploitation could facilitate spam campaigns, phishing, and data breaches, undermining trust and compliance for affected organizations.

The primary impact of CVE-2026-0829 is the unauthorized use of the affected WordPress site as an open mail relay, which can lead to widespread spam and phishing campaigns originating from legitimate domains, damaging domain reputation and potentially causing email blacklisting. This can disrupt legitimate email communications and harm organizational credibility. Additionally, the ability to guess file IDs and access uploaded files without authorization risks exposure of sensitive or confidential information, leading to data breaches and compliance violations (e.g., GDPR, HIPAA). While availability is not directly impacted, the reputational damage and potential legal consequences can be significant. Organizations relying on this plugin may face increased phishing risks, data leakage, and operational disruptions. The vulnerability’s ease of exploitation (no authentication or user interaction required) increases the likelihood of automated attacks and widespread abuse if left unmitigated.

1. Immediately update the Frontend File Manager plugin to a patched version once available from the vendor or developer. 2. If no patch is available, disable or remove the plugin temporarily to prevent exploitation. 3. Implement web application firewall (WAF) rules to block suspicious email sending requests and restrict access to file management endpoints. 4. Monitor outgoing email traffic for unusual volumes or patterns indicative of relay abuse. 5. Restrict file access permissions and consider implementing additional authentication or authorization layers for file retrieval endpoints. 6. Conduct regular audits of uploaded files to detect unauthorized access or data leaks. 7. Employ rate limiting and IP reputation filtering to reduce automated guessing of file IDs. 8. Educate site administrators on the risks of using plugins without proper security controls and encourage minimal plugin usage. 9. Review email server configurations to prevent open relay conditions beyond the plugin vulnerability. 10. Maintain up-to-date backups and incident response plans to quickly recover from potential data exposure or abuse.