Customer has experienced an issue with the AV engine after upgrade to CAS 3.1.5.1
CAS 3.1.5.1
Internal bug for Kaspersky AV engine on CAS 3.1.5.1 (CRE-12199)
Please upgrade to CAS 3.1.6.0
Workaround:
CAS > Services > AV Scanning Behavior > Kaspersky Options > Disable URL Checking