Inefficient Regular Expression Complexity in TorBot

Torbot is an open source tor network intelligence tool. In affected versions the `torbot.modules.validators.validate_link function` uses the python-validators URL validation regex. This particular regular expression has an exponential complexity which allows an attacker to cause an application crash using a well-crafted argument. An attacker can use a well-crafted URL argument to exploit the vulnerability in the regular expression and cause a Denial of Service on the system. The validators file has been removed in version 4.0.0. Users are advised to upgrade. There are no known workarounds for this vulnerability.

The validators package 0.12.2 through 0.12.5 for Python enters an infinite loop when validators.domain is called with a crafted domain string. This is fixed in 0.12.6.