bin/57442: mdnsd(8) privilege separation is broken

[campbell+netbsd%mumble.net@localhost]

>Number:         57442
>Category:       bin
>Synopsis:       mdnsd(8) privilege separation is broken
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat May 27 11:45:01 +0000 2023
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The NetMDNSD Foundation
>Environment:
>Description:
We have a pseudo-user _mdnsd for the use of mdnsd(8), but mdnsd(8) doesn't use it -- instead it uses the user nobody, which isn't supposed to be used by anybody.  It appears to have been lost in a 2018 update among merge conflicts.
>How-To-Repeat:
$ service mdnsd onestart
$ ps axuwww | grep mdnsd
>Fix:
Yes, please!