Elixir up to 1.18.5/1.19.6/1.20.4 JSON JSON.decode denial of service

Summaryinfo

A vulnerability, which was classified as problematic, was found in Elixir up to 1.18.5/1.19.6/1.20.4. This impacts the function JSON.decode of the component JSON Module. The manipulation results in denial of service. This vulnerability is identified as CVE-2026-115274. The attack can be executed remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Elixir up to 1.18.5/1.19.6/1.20.4. Affected is the function JSON.decode of the component JSON Module. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-115274 since 10/23/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 1.18.6, 1.19.7 or 1.20.5 eliminates this vulnerability.

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Productinfo

Name

• Elixir

Version

• 1.18.0
• 1.18.1
• 1.18.2
• 1.18.3
• 1.18.4
• 1.18.5
• 1.19.0
• 1.19.1
• 1.19.2
• 1.19.3
• 1.19.4
• 1.19.5
• 1.19.6
• 1.20.0
• 1.20.1
• 1.20.2
• 1.20.3
• 1.20.4

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