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.
Published: 2026-10-30
Score: 6.9 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Workaround

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().

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History

Fri, 30 Oct 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 30 Oct 2026 09:00:00 +0000

Type Values Removed Values Added
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.
Title Unbounded integer parsing in JSON.decode/1 enables CPU and memory exhaustion denial of service in Elixir
First Time appeared Elixir-lang
Elixir-lang elixir
Weaknesses CWE-1284
CPEs cpe:2.3:a:elixir-lang:elixir:*:*:*:*:*:*:*:*
Vendors & Products Elixir-lang
Elixir-lang elixir
References
Metrics cvssV4_0

{'score': 6.9, 'vector': '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'}


Subscriptions

Elixir-lang Elixir
cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-10-30T16:51:45.396Z

Reserved: 2026-10-23T12:45:01.103Z

Link: CVE-2026-115274

cve-icon Vulnrichment

Updated: 2026-10-30T16:51:40.079Z

cve-icon NVD

Status : Deferred

Published: 2026-10-30T09:17:14.103

Modified: 2026-10-30T19:39:14.897

Link: CVE-2026-115274

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-30T11:15:11Z

Weaknesses