CVE-2020-26153 in Event Espresso Core Plugin
Summary
by MITRE • 07/13/2021
A cross-site scripting (XSS) vulnerability in wp-content/plugins/event-espresso-core-reg/admin_pages/messages/templates/ee_msg_admin_overview.template.php in the Event Espresso Core plugin before 4.10.7.p for WordPress allows remote attackers to inject arbitrary web script or HTML via the page parameter.
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Analysis
by VulDB Data Team • 07/16/2021
This cross-site scripting vulnerability exists within the Event Espresso Core WordPress plugin affecting versions prior to 4.10.7.p. The flaw resides in the ee_msg_admin_overview.template.php file which processes user input through the page parameter without adequate sanitization or output encoding. Attackers can exploit this weakness by crafting malicious payloads that get executed in the context of a victim's browser when they view the affected administrative interface. The vulnerability specifically impacts the message administration overview page where the page parameter is directly incorporated into the HTML output without proper validation mechanisms.
The technical implementation of this XSS vulnerability demonstrates a classic failure in input validation and output encoding practices. The page parameter received from user input is directly echoed back into the HTML template without appropriate sanitization, creating an opportunity for attackers to inject malicious scripts that can execute in the browser context of authenticated administrators. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws where untrusted data is incorporated into web pages without proper validation or encoding. The attack vector requires minimal privileges as the vulnerability is present in the administrative interface that typically requires authentication, making it particularly dangerous for attackers who can gain access to administrative sessions.
The operational impact of this vulnerability extends beyond simple script injection as it can enable attackers to escalate privileges, steal session cookies, perform unauthorized administrative actions, or redirect users to malicious sites. Since the vulnerability affects the WordPress plugin's administrative interface, successful exploitation could allow attackers to modify event data, manipulate message templates, or potentially gain complete control over the Event Espresso functionality. The attack requires a victim with administrative privileges to view the malicious page parameter, making it particularly concerning for high-privilege accounts. According to ATT&CK framework, this vulnerability maps to T1059.001 which covers command and scripting interpreter techniques, and T1566 which covers credential access through social engineering or exploitation of software vulnerabilities.
Mitigation strategies for this vulnerability include immediate patching to version 4.10.7.p or later which implements proper input sanitization and output encoding for the page parameter. Organizations should also implement additional security measures such as Content Security Policy headers to limit script execution, regular security audits of WordPress plugins, and monitoring for suspicious administrative activity. Administrators should ensure that only necessary users have administrative privileges and implement multi-factor authentication to reduce the impact of potential exploitation. The vulnerability highlights the importance of input validation and output encoding practices in web applications, particularly within administrative interfaces where the potential for damage is significantly higher than in user-facing components. Security teams should also consider implementing web application firewalls to detect and block malicious payloads targeting known XSS patterns in WordPress environments.