CVE-2023-3082 in Post SMTP Plugin
Summary
by MITRE • 07/12/2023
The Post SMTP plugin for WordPress is vulnerable to Stored Cross-Site Scripting via email contents in versions up to, and including, 2.5.7 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 07/30/2023
The Post SMTP plugin for WordPress represents a critical security vulnerability classified as CVE-2023-3082, which affects versions up to and including 2.5.7. This vulnerability manifests as a stored cross-site scripting flaw that directly impacts the plugin's handling of email content within the WordPress ecosystem. The vulnerability stems from inadequate input sanitization mechanisms and insufficient output escaping routines that fail to properly validate or sanitize user-supplied data before processing. The flaw exists within the plugin's email processing pipeline where incoming email messages are stored and subsequently rendered in administrative interfaces, creating a persistent vector for malicious script injection. Attackers can exploit this weakness by crafting specially formatted email content that contains malicious javascript payloads, which then get stored in the plugin's database and executed whenever authorized users view the affected email messages.
The technical exploitation of this vulnerability occurs through the manipulation of email content fields within the Post SMTP plugin's administrative interface. When an attacker sends an email containing malicious script code to a WordPress site configured with this plugin, the script gets stored in the database without proper sanitization. The vulnerability is particularly concerning because it operates without requiring authentication, allowing unauthenticated attackers to compromise the system through email injection. This stored XSS vulnerability directly maps to CWE-79, which describes improper neutralization of input during web page generation in a web application, and aligns with ATT&CK technique T1566.001 for initial access through spearphishing attachments. The flaw specifically affects the plugin's email content rendering functionality where stored messages are displayed in administrative panels, creating a persistent threat vector that can compromise any user who accesses the affected pages.
The operational impact of CVE-2023-3082 extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, and privilege escalation within the WordPress environment. When authenticated administrators view compromised email messages, the malicious scripts can execute in their browser context, potentially allowing attackers to steal session cookies, modify administrative settings, or even gain full control over the WordPress installation. The vulnerability's persistence through storage means that the malicious code remains active until the affected email messages are manually deleted or the plugin is updated, creating an ongoing security risk for all users who access the compromised administrative interfaces. This threat is particularly severe in enterprise environments where WordPress administrators regularly process large volumes of email communications through the plugin.
Mitigation strategies for CVE-2023-3082 require immediate action to address the root cause through plugin updates and enhanced input validation measures. The primary recommendation involves upgrading to the latest version of the Post SMTP plugin where the vulnerability has been patched and proper input sanitization has been implemented. Organizations should also implement additional defensive measures including regular security audits of installed plugins, implementing content security policies to limit script execution, and monitoring email processing activities for suspicious patterns. Network-level protections such as web application firewalls can provide additional layers of defense by detecting and blocking malicious script payloads before they reach the application layer. Security teams should also consider implementing automated patch management systems to ensure timely deployment of security updates across all WordPress installations. The vulnerability highlights the importance of proper input validation and output escaping practices as outlined in OWASP Top Ten security guidelines, particularly focusing on preventing XSS attacks through proper sanitization of user-supplied content.