The latest Forge for 1.7.10 is from 6 years ago:
https://files.minecraftforge.net/net/minecraftforge/forge/index_1.7.10.html
For 1.10.2, it's been 4 years.
There are still plenty of public servers running modpacks from those versions, in fact I still play on one daily. Is the version of log4j used by them safe?