A vulnerability has been identified in CP-8000 MASTER MODULE WITH I/O -25/+70°C (All versions < CPC80 V16.30), CP-8000 MASTER MODULE WITH I/O -40/+70°C (All versions < CPC80 V16.30), CP-8021 MASTER MODULE (All versions < CPC80 V16.30), CP-8022 MASTER MODULE WITH GPRS (All versions < CPC80 V16.30). When using the HTTPS server under specific conditions, affected devices do not properly free resources. This could allow an unauthenticated remote attacker to put the device into a denial of service condition.
https://cert-portal.siemens.com/productcert/pdf/ssa-491621.pdf