HP has identified a security vulnerability with the I.R.I.S. OCR (Optical Character Recognition) software available with HP PageWide and OfficeJet printer software installations that could potentially allow unauthorized local code execution.
The Open Connectivity Foundation UPnP specification before 2020-04-17 does not forbid the acceptance of a subscription request with a delivery URL on a different network segment than the fully qualified event-subscription URL, aka the CallStranger issue.