Unbounded integer parsing in JSON.decode/1 enables CPU and memory exhaustion denial of service in Elixir
Summary
| CVE | CVE-2026-115274 |
|---|---|
| State | PUBLISHED |
| Assigner | EEF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-30 09:17:14 UTC |
| Updated | 2026-10-30 09:17:14 UTC |
| Description | Improper Validation of Specified Quantity in Input vulnerability in the Elixir standard library's JSON module allows an unauthenticated attacker who supplies a JSON document to cause a denial of service through CPU and memory exhaustion. JSON.decode/1 and JSON.decode!/1 convert each integer literal with erlang:binary_to_integer/1 and do not bound its length. A literal of one million digits decodes successfully but costs 100 to 300 times as much CPU as a string of the same length, so one request body of a few megabytes holds a scheduler for about a second. A literal of more than about 1.29 million digits raises SystemLimitError. Applications generated by phx.new decode request bodies with JSON in Plug.Parsers, before routing and authentication. This issue affects elixir: from 1.18.0-rc.0 before 1.18.6, from 1.19.0-rc.0 before 1.19.7, and from 1.20.0-rc.0 before 1.20.5. |
Risk And Classification
Primary CVSS: v4.0 6.9 MEDIUM from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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
Problem Types: CWE-1284 | CWE-1284 CWE-1284 Improper Validation of Specified Quantity in Input
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | Secondary | 6.9 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 6.9 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N |
CVSS v4.0 Breakdown
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Elixir-lang | Elixir | affected 1.18.0-rc.0 1.18.6 semver | Not specified |
| CNA | Elixir-lang | Elixir | affected 1.19.0-rc.0 1.19.7 semver | Not specified |
| CNA | Elixir-lang | Elixir | affected 1.20.0-rc.0 1.20.5 semver | Not specified |
| CNA | Elixir-lang | Elixir | affected 793c1147210388587defb649f25f293ffbfa6b1b * git | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/elixir-lang/elixir/security/advisories/GHSA-rp5q-xqhq-926h | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/elixir-lang/elixir/commit/7154e8781da9fd016a973ea01776a011c8b... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/elixir-lang/elixir/commit/cd158efacdc10b30232864251747dff9b83... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/elixir-lang/elixir/commit/ee5cc23f8928aa5a0f25bb7f28e42ecfc7b... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/elixir-lang/elixir/commit/793c1147210388587defb649f25f293ffbf... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| osv.dev/vulnerability/EEF-CVE-2026-115274 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | osv.dev | |
| github.com/elixir-lang/elixir/commit/c81f12265919c34a0d5134f1905a4eb4eda... | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| cna.erlef.org/cves/CVE-2026-115274.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | cna.erlef.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: David Vieira Kurz (en)
CNA: Peter Ullrich (en)
CNA: David Vieira Kurz (en)
CNA: José Valim (en)
CNA: Jonatan Männchen / EEF (en)
Additional Advisory Data
Workarounds
CNA: Decode untrusted JSON with an integer decoder that rejects long digit runs before conversion: defmodule SafeJSON do def decode!(binary) do case JSON.decode(binary, :ok, integer: &safe_integer/1) do {decoded, :ok, ""} -> decoded _ -> raise ArgumentError, "invalid JSON" end end defp safe_integer(digits) when byte_size(digits) <= 1024, do: String.to_integer(digits) defp safe_integer(_digits), do: raise(ArgumentError, "integer too long") end In Phoenix, pass SafeJSON to Plug.Parsers as json_decoder instead of Phoenix.json_library().