RnaUtility.dll in RsvcHost.exe 2.30.0.23 in Rockwell RSLogix 19 and earlier allows remote attackers to cause a denial of service (crash) via a crafted rna packet with a long string to TCP port 4446 that triggers (1) "a memset zero overflow" or (2) an out-of-bounds read, related to improper handling of a 32-bit size field.