I'm confused with what the firewall is triggering off of above. It seems like our check of the cookies set for the user is causing a flag, but I have no idea why. We're setting a standard cookie and we're simply checking if it's set. There's no SQL query involved there or anything else that should be problematic. We also haven't heard of this issue from any other users and there are many, many sites with mod_security enabled.
Did you customize the standard mod_security ruleset in some way? You may need to contact your host or technical support further to understand what's going on and why the block above is occurring.
Thanks,
Alex