CVE-2017-5476 in Serendipity
Summary
by MITRE
Serendipity through 2.0.5 allows CSRF for the installation of an event plugin or a sidebar plugin.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/13/2026
The vulnerability identified as CVE-2017-5476 affects Serendipity, a popular content management system that has been widely used for blog and website management. This issue represents a significant security weakness in the application's authentication and authorization mechanisms, specifically within the plugin installation functionality. The vulnerability allows authenticated users to perform cross-site request forgery attacks that could enable the installation of malicious plugins, potentially compromising the entire web application and underlying server infrastructure. The affected version range includes Serendipity through 2.0.5, indicating this flaw has existed for several years and likely affected numerous deployments.
The technical flaw stems from insufficient anti-CSRF protection mechanisms within the plugin installation endpoints. When administrators or users with appropriate privileges attempt to install plugins through the web interface, the application fails to properly validate the origin of the requests. This absence of proper CSRF token verification means that an attacker could craft malicious requests that would be executed by authenticated users without their knowledge or consent. The vulnerability specifically impacts both event plugins and sidebar plugins, which are critical components that can execute arbitrary code and modify application behavior. The lack of proper request validation creates an attack surface where malicious actors can leverage existing user sessions to install unauthorized plugins, potentially gaining persistent access to the system.
The operational impact of this vulnerability extends far beyond simple privilege escalation. Successful exploitation could enable attackers to install backdoors, malware, or other malicious components that persist even after the initial attack. Sidebar plugins are particularly dangerous as they execute on every page load and can intercept user data, modify content, or redirect traffic. Event plugins can hook into various application events and potentially modify core functionality or access sensitive data. This vulnerability essentially allows attackers to maintain persistent presence within the application environment, making it a severe threat to data integrity and system availability. The impact is compounded by the fact that many administrators may not immediately notice the unauthorized plugin installations, allowing the compromise to persist undetected for extended periods.
Mitigation strategies for CVE-2017-5476 should focus on implementing proper CSRF protection mechanisms throughout the application. The most effective approach involves ensuring that all plugin installation endpoints require valid CSRF tokens that are generated per-user session and validated on each request. This aligns with CWE-352, which specifically addresses Cross-Site Request Forgery vulnerabilities in web applications. Organizations should also implement proper input validation and access controls to ensure that only authorized users can install plugins. Additionally, the application should log all plugin installation activities and implement monitoring for unusual or unauthorized installations. The fix should include proper session management and token regeneration after authentication to prevent session hijacking attacks that could compound the CSRF vulnerability. Security practitioners should also consider implementing network-based monitoring and intrusion detection systems to identify suspicious plugin installation patterns. This vulnerability demonstrates the critical importance of maintaining proper authentication controls and input validation in web applications, as highlighted in various ATT&CK framework techniques related to privilege escalation and persistence mechanisms.