Hello,
All versions prior to 2.78 are vulnerable.
Has there been any change on the avast side?
Many people who had the problem before the last update no longer have it now.
However,their router has not been updated, the detected version of dnsmasq is still "dnsmasq-2.55"
I would like to point out that the wifi-inspector scan was done by mentioning "Home" network , because in "Public" network (selected), avast had not detected for several months now, which is normal when we know that the vulnerability is positioned on the LAN and not the WAN.
nb:This is an observation of several (Belgian) users and not mine, because my router was updated at the end of the year with dnsmasq 2.78