CVE-2020-19949 in YzmCMS
Summary
by MITRE • 09/24/2021
A cross-site scripting (XSS) vulnerability in the /link/add.html component of YzmCMS v5.3 allows attackers to execute arbitrary web scripts or HTML.
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Analysis
by VulDB Data Team • 10/02/2021
The vulnerability identified as CVE-2020-19949 represents a critical cross-site scripting flaw within the YzmCMS content management system version 5.3, specifically affecting the /link/add.html component. This issue falls under the Common Weakness Enumeration category CWE-79, which defines improper neutralization of input during web page generation as a fundamental weakness in web applications. The vulnerability arises from insufficient validation and sanitization of user-supplied input parameters that are directly reflected in the web page output without proper encoding or escaping mechanisms.
The technical exploitation of this XSS vulnerability occurs when an attacker crafts malicious input within the link addition form component of the CMS. When the application processes this input and renders it back to the user interface without adequate sanitization, the malicious script code becomes executable within the victim's browser context. This allows attackers to inject arbitrary JavaScript code, HTML markup, or other malicious content that can persist in the application's database and execute whenever the affected page is accessed by other users. The vulnerability's impact extends beyond simple script execution as it can enable session hijacking, credential theft, and the delivery of malware to unsuspecting users.
From an operational perspective, this vulnerability presents a significant risk to organizations utilizing YzmCMS v5.3, as it allows attackers to compromise user sessions and potentially gain unauthorized access to administrative functions. The attack vector requires minimal privileges since the vulnerability exists in a publicly accessible component that does not require authentication to exploit. The persistent nature of the XSS flaw means that once exploited, malicious code can affect multiple users over time until the vulnerability is patched. This makes the vulnerability particularly dangerous in environments where the CMS is used for public-facing websites or community platforms where user-generated content is common.
The remediation strategy for this vulnerability involves implementing comprehensive input validation and output encoding mechanisms throughout the application's data handling pipeline. Organizations should immediately upgrade to a patched version of YzmCMS v5.3 or apply the vendor-provided security patches to address the XSS vulnerability. Additionally, implementing Content Security Policy (CSP) headers can provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be loaded and executed. Security teams should also conduct thorough code reviews to identify similar input validation weaknesses in other components of the application and establish proper sanitization procedures for all user-supplied data before it is processed or stored within the system. The vulnerability demonstrates the critical importance of maintaining up-to-date security practices and the potential consequences of inadequate input validation in web applications.