CVE-2026-75758 Unbounded recursion between Inspect.List charlist rendering and List.to_string/1 error path in Elixir
An attacker can cause a denial of service by triggering unbounded recursion in Elixir's list inspection functions, exhausting memory.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-75758?
CVE-2026-75758 is a medium-severity denial of service vulnerability in elixir-lang elixir, published on 28 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
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.
Weakness: CWE-674
Which versions are affected by CVE-2026-75758?
How do I fix CVE-2026-75758?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-75758 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-75758 exists.
Sources
Also known as AZL-98220, DEBIAN-CVE-2026-75758, EEF-CVE-2026-75758, GHSA-jf5q-v438-665c, UBUNTU-CVE-2026-75758.