CVE-2021-4231: 
JavaScript vulnerability analysis and mitigation

A cross-site scripting (XSS) vulnerability was discovered in Angular versions up to 11.0.4 and 11.1.0-next.2. The vulnerability affects the handling of comments and was disclosed on January 22, 2021. The issue allows for potential XSS attacks in development environments when Server-Side Rendering (SSR) is enabled (Angular Commit, Snyk Report).

The vulnerability occurs because HTML does not specify a way to escape comment end text inside comments. When manipulating comment text, it's possible to prematurely close a comment by including specific sequences like '-->', potentially leading to XSS attacks. This becomes particularly dangerous when using operations like 'div.innerHTML = div.innerHTML' where comment text is not properly escaped (Angular Issue).

The vulnerability could allow attackers to execute malicious scripts through comment manipulation, potentially leading to session hijacking, data theft, or other malicious activities. The impact is primarily limited to development environments where SSR is enabled (Snyk Report).

The vulnerability was fixed in Angular versions 11.0.5 and 11.1.0-next.3. Users should upgrade to these or later versions to address the issue. The fix involves escaping comment text by surrounding '<' and '>' with zero-width spaces to prevent premature comment closure while maintaining normal rendering (Angular Commit).