Regular Expression Denial of Service in npm-user-validate

npm-user-validate before version 1.0.1 is vulnerable to a Regular Expression Denial of Service (REDos). The regex that validates user emails took exponentially longer to process long input strings beginning with @ characters.

Impact

The issue affects the email function. If you use this function to process arbitrary user input with no character limit the application may be susceptible to Denial of Service.

Patches

The issue is patched in version 1.0.1 by improving the regular expression used and also enforcing a 254 character limit.

Workarounds

Restrict the character length to a reasonable degree before passing a value to .emal(); Also, consider doing a more rigorous sanitizing/validation beforehand.