The SIP implementation in Cisco Unified Communications Manager (CM) 8.6(.2) and earlier allows remote authenticated users to cause a denial of service (process crash) via a crafted SIP message that is not properly handled during processing of an XML document, aka Bug ID CSCtq76428.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.