CVE-2015-2289 in Serendipity
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in templates/2k11/admin/entries.tpl in Serendipity before 2.0.1 allows remote authenticated editors to inject arbitrary web script or HTML via the serendipity[cat][name] parameter to serendipity_admin.php, when creating a new category.
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Analysis
by VulDB Data Team • 05/01/2022
The CVE-2015-2289 vulnerability represents a critical cross-site scripting flaw within the Serendipity blogging platform, specifically affecting versions prior to 2015.02.01. This vulnerability exists within the administrative template file entries.tpl located in the 2k11 theme directory, making it exploitable through the web-based administrative interface. The flaw is particularly concerning because it targets authenticated editors who possess administrative privileges, thereby expanding the potential attack surface beyond typical unauthenticated XSS vectors. The vulnerability manifests when a malicious user with editor privileges attempts to create a new category through the serendipity_admin.php administrative endpoint, specifically targeting the serendipity[cat][name] parameter.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within the Serendipity content management system's administrative interface. When an authenticated editor submits a category name containing malicious script code through the targeted parameter, the system fails to properly escape or filter the input before rendering it within the HTML output context. This failure creates a persistent XSS vector where the malicious payload executes in the context of other users' browsers who view the affected category listings. The vulnerability is classified as a reflected XSS variant since the malicious content is processed and stored within the application's database before being served back to users, making it particularly dangerous for long-term persistence. According to CWE classification, this represents a CWE-79: Improper Neutralization of Input During Web Page Generation, which falls under the broader category of input validation failures.
The operational impact of CVE-2015-2289 extends beyond simple script execution, as it provides attackers with the ability to compromise user sessions, steal sensitive information, and potentially escalate privileges within the blogging platform. An attacker could craft malicious category names that, when viewed by other administrators or editors, would execute scripts to steal session cookies, redirect users to phishing sites, or inject malicious content into the platform's administrative interface. This vulnerability undermines the trust model of the administrative system, as authenticated users can be exploited without their knowledge, potentially leading to complete platform compromise. The attack requires only basic administrative privileges, making it particularly dangerous in environments where multiple users have editor access. The vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically targeting web-based scripting environments where user input is improperly sanitized.
Mitigation strategies for this vulnerability involve immediate patching of the affected Serendipity versions to 2.0.1 or later, which includes proper input sanitization and output escaping mechanisms. Organizations should implement comprehensive input validation for all administrative parameters, particularly those used in template rendering contexts. The solution requires proper HTML escaping of user-supplied data before rendering within web pages, utilizing context-appropriate encoding mechanisms such as HTML entity encoding for HTML content contexts. Additionally, implementing Content Security Policy (CSP) headers can provide defense-in-depth measures to prevent script execution even if XSS vectors are somehow bypassed. Regular security audits of template files and administrative interfaces should be conducted to identify similar input validation gaps. The vulnerability highlights the importance of principle of least privilege in administrative access, where editor accounts should have minimal necessary permissions to reduce the attack surface. Organizations should also consider implementing web application firewalls to detect and block suspicious parameter values, particularly those containing common XSS payload patterns such as script tags, javascript protocols, or event handlers.