SIP softphone buffer overflow demo
Last updated: Apr 17, 2020
Someone was showing off a 0day exploit at Black Hat. The article is a bit sketchy and feels sensational, but it does show that various parties are concerned. Just like most other pieces of software, softphones will (and do) have security vulnerabilities lead to remote access.
Article can be found here.
Hardphones, on the other hand, are secure.. right? :-p