Hi John,
What you are referring to with 22.16.0 is the version of node that is bundled with emsdk. We don't tend to update this very often, for various reasons. Note that emscripten uses node only for its internal JS compiler. This means its only used to process your code, not, for example, untrusted code from the internet.
If you have concerns about it fairly easy to just avoid using it. You can configure emscripten to use any version of node you like (by setting `NODE=` in your config file or `EM_NODE=` as an environment variable).
For example, if you would prefer to use your linux distributions version of node with emscripten you should be able to simply `export EM_NODE=/usr/bin/node`. You could instead edit `/path/to/emsdk/.emscripten` config file (but you may need to re-edit this each time you run emsdk installs a new version).
cheers,
sam