connorskees grass visitor denial of service

A vulnerability has been found in connorskees grass up to 0.13.4. The impacted element is the function grass_compiler::selector::extend/grass_compiler::evaluate::visitor. The manipulation leads to denial of service. The attack must be carried out locally. The exploit has been disclosed to the public and may be used. The project maintainer explains: "DoS vulnerabilities are generally fine in Sass compilers -- they are trivially possible with recursive functions, infinite loops, nested mixins, etc. The description here is wrong. Compile time is not expected to be linear relative to the input, and the @extend algorithm is definitionally exponential."