Are extensions which haven't been updated in 9 years safe to use? Common sense tells me no, but I don't know if these extensions, being open source, are regularly checked by anyone on MediaWiki? I can't find any evidence of a comprehensive audit ever been done on the extensions though.
Specifically, Extension:Wiki-httpbl hasn't been updated in 9 years and appears to be unmaintained. Same goes for Extension:GroupPermissions - would it be better to archive these extensions if they haven't been audited?