LuaTeX before 1.17.0 allows execution of arbitrary shell commands when compiling a TeX file obtained from an untrusted source. This occurs because luatex-core.lua lets the original io.popen be accessed. This also affects TeX Live before 2023 r66984 and MiKTeX before 23.5.
LuaTeX before 1.17.0 allows a document (compiled with the default settings) to make arbitrary network requests. This occurs because full access to the socket library is permitted by default, as stated in the documentation. This also affects TeX Live before 2023 r66984 and MiKTeX before 23.5.