Mumble before 1.3.4 allows remote code execution if a victim navigates to a crafted URL on a server list and clicks on the Open Webpage text.
https://security.gentoo.org/glsa/202105-13
https://lists.debian.org/debian-lts-announce/2021/02/msg00022.html
https://github.com/mumble-voip/mumble/pull/4733
https://github.com/mumble-voip/mumble/compare/1.3.3...1.3.4
https://github.com/mumble-voip/mumble/commit/e59ee87abe249f345908c7d568f6879d16bfd648