Squid 3.0 through 3.0.STABLE16 and 3.1 through 3.1.0.11 allows remote attackers to cause a denial of service via malformed requests including (1) \missing or mismatched protocol identifier \ (2) missing or negative status value \ (3) \missing version \ or (4) \missing or invalid status number \ related to (a) HttpMsg.cc and (b) HttpReply.cc.