Algorithmic complexity vulnerability in Address.pm in the Email-Address module 1.908 and earlier for Perl allows remote attackers to cause a denial of service (CPU consumption) via a crafted string containing a list of e-mail addresses in conjunction with parenthesis characters that can be associated with nested comments. NOTE: the default configuration in 1.908 mitigates this vulnerability but misparses certain realistic comments.
https://forum.bestpractical.com/t/security-vulnerabilities-in-rt-2017-06-15/32016