CVE-2020-16131 in Tiki
Summary
by MITRE
Tiki before 21.2 allows XSS because [\s\/"\'] is not properly considered in lib/core/TikiFilter/PreventXss.php.
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Analysis
by VulDB Data Team • 08/04/2020
The vulnerability identified as CVE-2020-16131 affects Tiki versions prior to 21.2 and represents a cross-site scripting weakness that stems from inadequate input validation within the TikiFilter::PreventXss.php component. This flaw specifically manifests when the regular expression pattern [\s\/"\'] fails to adequately sanitize user-supplied data, creating opportunities for malicious actors to inject harmful scripts into web applications. The vulnerability resides in the core filtering mechanism designed to prevent XSS attacks, thereby undermining the application's security posture and potentially allowing unauthorized code execution within users' browsers.
The technical implementation of this vulnerability demonstrates a classic improper input sanitization issue that aligns with CWE-79, which describes cross-site scripting vulnerabilities resulting from insufficient validation of user input. The flaw occurs because the regular expression pattern [\s\/"\'] does not comprehensively address all potential XSS attack vectors, leaving gaps that attackers can exploit to bypass security measures. When users submit content containing malicious scripts, the inadequate filtering allows these payloads to persist within the application's data structures and subsequently render in other users' browsers, creating a persistent threat vector.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. An attacker could craft specially formatted input that appears benign to the application's filtering logic but contains embedded JavaScript that executes when other users view the content. This type of vulnerability particularly affects web applications that rely heavily on user-generated content, as it creates a persistent threat vector that can compromise user sessions and potentially lead to full system compromise. The vulnerability's presence in Tiki's core filtering system means that it affects multiple application modules and functionalities that depend on this security mechanism.
Organizations utilizing affected Tiki versions should prioritize immediate remediation through the application of the vendor-provided patch or upgrade to version 21.2 and later. The mitigation strategy should include comprehensive input validation at multiple layers, including client-side and server-side sanitization, to ensure that all user-supplied content undergoes rigorous security screening. Additionally, implementing Content Security Policy headers and regular security audits can help detect and prevent similar vulnerabilities in the future. Security teams should also consider implementing automated scanning tools that can identify XSS vulnerabilities in web applications, as this particular flaw demonstrates how seemingly minor oversights in regular expression patterns can create significant security risks. The vulnerability's classification under ATT&CK technique T1203, which covers exploitation of web application vulnerabilities, underscores the importance of maintaining up-to-date security measures and comprehensive testing protocols to prevent exploitation attempts.