CVE-2020-5263: 
JavaScript vulnerability analysis and mitigation

CVE-2020-5263 affects auth0.js npm package versions 8.0.0 through 9.13.1 (inclusive). The vulnerability was discovered and disclosed on April 9, 2020. The issue involves information disclosure through error objects, where authentication errors could expose plaintext user passwords if the error object is logged or displayed without proper filtering (GitHub Advisory).

The vulnerability occurs when an authentication error happens, causing the error object returned by the library to contain the original request data including the user's plaintext password. This sensitive information remains exposed in the error object if it is logged or displayed without modification. The vulnerability has been assigned a Moderate severity rating (GitHub Advisory).

If an application stores or displays error objects without proper filtering, it risks exposing users' plaintext passwords. This could lead to unauthorized access to user accounts if the error logs or displays are accessible to malicious actors (GitHub Advisory).

The recommended mitigation is to upgrade auth0.js to version 9.13.2 or later, where user passwords are properly masked in error objects. If immediate upgrading is not possible, developers should implement temporary fixes by ensuring error objects are not stored or displayed publicly without proper filtering of sensitive information (GitHub Advisory).