I also checked f/w updates for my routers this past weekend(different manufacturer). I saw the newer one has the recent security fixes, but the older model does not. It could be the older model isn't affected, but I highly suspect they simply didn't bother to fix. (I prefer a light power draw on main router than these newer ones which pull over double the wattage. I guess I can turn off the wifi to lessen the draw).
I remember another recent dir 615 post that sounded familiar to yours.
Update: I double checked and found updates for those issues for my router dated 4/24. (The day I was looking was returning site issues/errors). I will install this weekend.