CVE-2020-4052 in Wiki.js
Summary
by MITRE
In Wiki.js before 2.4.107, there is a stored cross-site scripting through template injection. This vulnerability exists due to an insecure validation mechanism intended to insert v-pre tags into rendered HTML elements which contain curly-braces. By creating a crafted wiki page, a malicious Wiki.js user may stage a stored cross-site scripting attack. This allows the attacker to execute malicious JavaScript when the page is viewed by other users. This has been patched in 2.4.107.
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Analysis
by VulDB Data Team • 10/24/2020
The vulnerability described in CVE-2020-4052 represents a critical stored cross-site scripting flaw in Wiki.js versions prior to 2.4.107, specifically targeting the template injection mechanism that handles v-pre tags in rendered HTML content. This vulnerability stems from an insecure validation mechanism that was designed to properly insert v-pre tags into HTML elements containing curly braces, which are commonly used in templating systems. The flaw allows malicious actors to exploit the system's template processing logic by crafting specially formatted wiki pages that contain malicious JavaScript code within template variables.
The technical implementation of this vulnerability occurs when Wiki.js processes wiki pages containing template syntax with curly braces, where the system incorrectly validates and processes these elements without proper sanitization. The insecure validation mechanism fails to adequately distinguish between legitimate template syntax and malicious script content, creating an injection vector that enables attackers to embed JavaScript code within the rendered HTML output. When other users view the compromised wiki page, the malicious JavaScript executes in their browser context, potentially leading to session hijacking, credential theft, or other malicious activities.
The operational impact of this vulnerability extends beyond simple XSS exploitation as it provides attackers with persistent access to the wiki application's user base. Since the vulnerability is stored in the wiki database rather than being reflected in URLs or request parameters, the malicious payload remains active until manually removed or the system is updated. This persistent nature makes it particularly dangerous for collaborative environments where multiple users regularly access wiki content. The vulnerability affects any user with sufficient privileges to create or edit wiki pages, potentially allowing attackers to escalate their privileges or compromise the entire wiki instance.
Security professionals should note that this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and demonstrates a classic case of insufficient input validation in template processing systems. The ATT&CK framework categorizes this vulnerability under T1059.007 for scripting languages and T1566 for spearphishing attachments, as attackers could leverage this vulnerability to deliver malicious payloads through compromised wiki content. Organizations should immediately implement the patch available in Wiki.js version 2.4.107, which addresses the insecure validation mechanism by properly sanitizing template variables and ensuring that v-pre tags are correctly applied without allowing malicious content injection. Additionally, administrators should review user permissions and implement content filtering mechanisms to limit the potential impact of compromised accounts, while monitoring for suspicious page creation or modification activities that might indicate exploitation attempts.