ModSecurity author Ivan Ristic just reported that a ModSecurity evasion vulnerability has been published without him being notified in advance, so there is no update available yet. Check here for his announcement. And here for the advisory. Ivan Ristic suggests everyone to use this workaround until an updated version of ModSecurity is released (put on a single line):
SecRule REQUEST_BODY “@validateByteRange 1-255” “log,deny,phase:2,t:none,msg:’ModSecurity ASCIIZ Evasion Attempt'”
I’ve been using that rule for an hour or so, and have seen no false positives so far.