CVE-2020-7754: 
JavaScript vulnerability analysis and mitigation

CVE-2020-7754 affects the npm-user-validate package versions before 1.0.1. The vulnerability was discovered in January 2020 and involves a Regular Expression Denial of Service (ReDoS) vulnerability in the email validation functionality (GitHub Advisory).

The vulnerability exists in the email validation function where the regex that validates user emails took exponentially longer to process long input strings beginning with @ characters. This implementation flaw could lead to a Regular Expression Denial of Service (ReDoS) condition (GitHub Advisory).

If the vulnerable function is used to process arbitrary user input with no character limit, the application may be susceptible to Denial of Service attacks. The impact is considered Low severity according to security assessments (GitHub Advisory).

The vulnerability can be exploited by providing long input strings beginning with @ characters to the email validation function, causing the application to consume excessive resources (GitHub Advisory).

The vulnerability was patched in version 1.0.1 by improving the regular expression used and enforcing a 254 character limit. As a workaround, users can restrict the character length before passing a value to the email validation function and implement more rigorous sanitizing/validation beforehand (GitHub Advisory).