CVE-2026-75758: Unbounded recursion between Inspect.List charlist rendering and…

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.

Scores

CVSS scores of CVE-2026-75758, by who scored it
Scored by	CVSS	Score	Vector
EEFCNA (assigner)	4.0	Medium5.9	CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
NVDNVD · Deferred	4.0	Medium5.9	CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS (exploitation in 30 days): 0.18% · top 92% of all CVEs (6 Nov 2026)
CISA SSVC: Exploitation: poc · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.9.

Weakness

CWE-674 Uncontrolled Recursion (opens in a new tab)All about CWE-674 and its CVEs

Affected products

elixir-lang · elixir
- affected 1.15.0-rc.0 – < 1.18.5
- affected 1.19.0-rc.0 – < 1.19.6
- affected 1.20.0-rc.0 – < 1.20.4
elixir-lang · elixir
- affected 9718f2b90ce086ff8614d5782f4ec528495c98dd – < *

What to do

Workaround: Install a global inspect function that renders lists as lists rather than inferring charlists, by calling Inspect.Opts.default_inspect_fun/1 with fn term, opts -> Inspect.inspect(term, %{opts | charlists: :as_lists}) end from the application's start callback. This keeps the charlist branch from being entered at all, so the mis-inferred conversion never raises and the error path cannot recurse. The trade-off is global: charlists then render in bracket form, so ~c"abc" inspects as [97, 98, 99] everywhere in the application, including in logs and error reports.

References (7)

Sources

The same CVE in the primary databases and aggregators, to check against.

Badge for a README or a ticket

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Record last updated 28 Aug 2026, 18:29 UTC.

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