CVE-2026-82404

Updated on 02 Sep 2026

Severity

8.3 High severity

Details

CVSS score
8.3
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L

Overview

About vulnerability

TOON is a compact, human-readable serialization of JSON data for LLM prompts. Prior to 2.3.1, decoding attacker-controlled TOON with a proto, constructor, or prototype key wrote through the object prototype chain instead of creating an own property, polluting Object.prototype for the runtime. In packages/toon/src/decode/expand.ts, the expandPaths: ‘safe’ path and insertPathSafe function made dotted keys such as a.proto.x the strongest vector, while plain nested objects, tabular rows, quoted keys, and streaming decode were also affected. The encoder also dropped own proto properties and could invoke an inherited setter during normalization. Services that decode untrusted TOON could experience denial of service or, when a suitable downstream gadget is present, remote code execution. This issue is fixed in version 2.3.1.

Details

Affected product:
toon , zephyr-packages
Affected packages:
create-zephyr-apps @ 0.2.0 (+26 more)