Bug 2542066

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Uncontrolled Recursion vulnerability in the Elixir standard library allows an attacker who controls a list passed to inspect/1, List.to_string/1, or List.to_charlist/1 to exhaust a BEAM node's memory.

Inspect.List's charlist branch in lib/elixir/lib/inspect.ex classifies a list as a charlist using List.ascii_printable?/2, which examines only the first :printable_limit (4096 by default) elements, and then calls IO.chardata_to_string/1 on the whole term. A list whose printable prefix exceeds that limit but which contains a later element that is not a code point (an atom, an out-of-range integer, or an improper tail) is therefore mis-classified, and the conversion raises ArgumentError. That conversion runs inside List.to_string/1, whose rescue clause builds its message by interpolating inspect(list), which re-enters the same branch and raises again. The nested inspection is an argument to raise, so the recursion is not in tail position and every level is retained: the process stack grows monotonically while each cycle re-walks the list, until the process is killed by max_heap_size or, by default, the node runs out of memory. List.to_charlist/1 has the same rescue shape.

Below the printable limit the inner inspect/1 sees the invalid element within its counter and renders the list in ordinary bracket form, so a single ArgumentError is raised and no recursion occurs.

This issue affects elixir: from 1.15.0-rc.0 before 1.18.5, from 1.19.0-rc.0 before 1.19.6, and from 1.20.0-rc.0 before 1.20.4.