CVE-2026-75758Unbounded recursion between Inspect.List charlist rendering and List.to_string/1 error path in Elixir

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://github.com/elixir-lang/elixir/security/advisories/GHSA-jf5q-v438-665c vendor-advisory, related
• https://cna.erlef.org/cves/CVE-2026-75758.html related
• https://osv.dev/vulnerability/EEF-CVE-2026-75758 related
• https://github.com/elixir-lang/elixir/commit/1eff1acffd49bdcc0d7f57ca74c1603328eed68a patch
• https://github.com/elixir-lang/elixir/commit/5230d73968f1b4969d2a2646786fa6c71475f5cc patch
• https://github.com/elixir-lang/elixir/commit/a983c8c043b1fbf1d95df78a29149222dac2988c patch
• https://github.com/elixir-lang/elixir/commit/0bba5887577b1e328da825bd018815fdc519685a patch