CVE-2021-37916: 
JavaScript vulnerability analysis and mitigation

Joplin before version 2.0.9 contained a Cross-Site Scripting (XSS) vulnerability that allowed attackers to execute malicious code via button and form elements in the note body (Joplin Release, NVD). The vulnerability was discovered and reported in August 2021, affecting all versions of Joplin prior to the 2.0.9 release.

The vulnerability existed due to insufficient filtering of HTML form elements in the note body. The application did not properly sanitize button and form elements, which could be exploited to inject malicious code. The fix involved adding additional HTML elements to the disallowedTags list, including 'button', 'form', 'input', 'select', 'textarea', 'option', and 'optgroup' (Joplin Commit).

The XSS vulnerability could allow attackers to execute arbitrary web script code in the context of the user's browser session. This could potentially lead to theft of sensitive information, session hijacking, or other malicious actions performed in the context of the authenticated user.

The vulnerability was fixed in Joplin version 2.0.9 by adding form-related elements to the disallowedTags list in the HTML sanitization process. Users should upgrade to version 2.0.9 or later to protect against this vulnerability (Joplin Release).