GHSA-xgh6-85xh-479p: 
JavaScript vulnerability analysis and mitigation

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in npm-user-validate package versions 1.0.0 and below, identified as GHSA-xgh6-85xh-479p. The vulnerability was discovered and published on October 16, 2020, affecting the email validation functionality of the package. The issue was found in the regex pattern used to validate user email addresses, which exhibited exponential processing time when handling long input strings beginning with @ characters (GitHub Advisory).

The vulnerability specifically affects the email validation function in npm-user-validate. The core issue lies in the implementation of the regular expression pattern used for email validation, which demonstrates exponential time complexity when processing certain input patterns. The vulnerability has been assigned a CVSS 3.1 Base Score of 7.5 (HIGH) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (NVD).

When exploited, this vulnerability can lead to Denial of Service conditions in applications using the affected function to process arbitrary user input without character limits. The impact is primarily focused on service availability, with no direct effect on confidentiality or integrity (GitHub Advisory).

The vulnerability was patched in version 1.0.1 of npm-user-validate, which improved the regular expression pattern and implemented a 254-character limit. For users unable to update immediately, recommended workarounds include restricting character length before passing values to the email validation function and implementing more rigorous input sanitization and validation (GitHub Advisory).