CVE-2023-2578 in Buy Me a Coffee Plugin
Summary
by MITRE • 07/10/2023
The Buy Me a Coffee WordPress plugin before 3.7 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 07/16/2023
The vulnerability identified as CVE-2023-2578 affects the Buy Me a Coffee WordPress plugin version 3.6 and earlier, representing a critical security flaw that undermines the integrity of WordPress multisite environments. This issue stems from insufficient input sanitization and output escaping mechanisms within the plugin's administrative settings, creating a pathway for privilege escalation attacks. The vulnerability specifically targets high-privilege users including administrators who possess the capability to modify plugin configurations, making it particularly dangerous in multi-user environments where security boundaries are paramount.
The technical implementation of this vulnerability resides in the plugin's failure to properly sanitize user-supplied data within its settings interface. When administrators configure the plugin's parameters, the input values are not adequately filtered or escaped before being stored in the database and subsequently rendered back to users. This oversight creates a persistent cross-site scripting vector that allows attackers to inject malicious scripts into the plugin's administrative interface. The flaw becomes particularly significant in multisite configurations where the unfiltered_html capability is typically restricted to prevent arbitrary HTML injection, yet the vulnerability circumvents these protections through the plugin's insufficient sanitization routines.
From an operational perspective, this vulnerability enables sophisticated attack scenarios where compromised administrators can execute malicious scripts against other users within the same WordPress network. The stored nature of the XSS vulnerability means that the malicious code persists in the database and executes whenever affected users access the plugin's settings page, potentially leading to session hijacking, data exfiltration, or further privilege escalation. The attack vector is particularly concerning because it operates within the administrative interface where users trust the system's security controls, making detection and mitigation more challenging for security monitoring systems.
The vulnerability aligns with CWE-79, which specifically addresses Cross-Site Scripting flaws in web applications, and demonstrates how inadequate input validation can compromise web application security. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1566.001 (Phishing: Spearphishing Attachment) as attackers can leverage the stored XSS to deliver malicious payloads to other users. The plugin's failure to implement proper security controls represents a gap in the principle of least privilege, where administrative functions should enforce strict input validation regardless of user permissions or security context.
The recommended mitigation strategy involves immediate upgrading to version 3.7 or later of the Buy Me a Coffee plugin, which contains the necessary sanitization and escaping fixes. Additionally, administrators should review and audit existing plugin configurations to identify any potentially injected malicious scripts that may have been stored during the vulnerable period. Network segmentation and monitoring solutions should be enhanced to detect unusual patterns in plugin settings modifications, while security teams should implement regular vulnerability assessments to identify similar sanitization gaps in other WordPress plugins. The incident underscores the critical importance of proper input validation in web applications and the necessity of maintaining up-to-date security practices in content management systems.