I am using core rule set 3.0.2 with latest libmodsecurity built from v3/master on nginx.
By appending the following to rule 942420 for example with:
|!REQUEST_COOKIES:Example.Session
I am able to successfully ignore the offending cookie.
However if I do the same to cover any of my Example cookies like this:
|!REQUEST_COOKIES:/Example/
The target is not respected and the cookie is blocked.
I have also tried variations like /^Example/ or /^Example\./ and cannot make the target match.