An issue was discovered in slicer69 doas before 6.2 on certain platforms other than OpenBSD. On platforms without strtonum(3), sscanf was used without checking for error cases. Instead, the uninitialized variable errstr was checked and in some cases returned success even if sscanf failed. The result was that, instead of reporting that the supplied username or group name did not exist, it would execute the command as root.
doas
CVE-2019-15901
An issue was discovered in slicer69 doas before 6.2 on certain platforms other than OpenBSD. A setusercontext(3) call with flags to change the UID, primary GID, and secondary GIDs was replaced (on certain platforms: Linux and possibly NetBSD) with a single setuid(2) call. This resulted in neither changing the group id nor initializing secondary group ids.