The issue allows HTML files crafted to look like jpg files to be uploaded, enabling cross-site scripting (XSS) attacks. This affects front-end forms with asset fields without mime type validation, asset fields in the control panel, and the asset browser in the control panel. If the XSS is crafted in a specific way, the "copy password reset link" feature can be exploited to gain access to a user's password reset token and their account. The authorized user must execute the XSS for the vulnerability to occur.