CVE-2021-38143: 
NixOS vulnerability analysis and mitigation

A stored Cross-Site Scripting (XSS) vulnerability was discovered in Form Tools through version 3.0.20, identified as CVE-2021-38143. The vulnerability was found in the customer account functionality, where when an administrator creates a customer account, the customer can log in and modify their name and last name fields. These fields are vulnerable to XSS payload insertion, which gets triggered in the admin panel when administrators view the client list (NVD).

The vulnerability is classified as CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'). It has a CVSS v3.1 base score of 6.1 (MEDIUM), with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N. The vulnerability requires user interaction and can lead to the extraction of the PHPSESSID cookie belonging to the administrator (NVD).

The successful exploitation of this vulnerability could allow an attacker to steal the administrator's PHPSESSID cookie through stored XSS attacks. This could potentially lead to session hijacking and unauthorized access to administrative functions (NVD).

The vulnerability affects Form Tools versions through 3.0.20. Users should upgrade to a patched version of Form Tools if available. As a general security practice, implementing proper input validation and output encoding for user-supplied data can help prevent XSS attacks (Form Tools).