CVE-2026-77415: Jsonata-Js Jsonata

Critical severity, CVSS 9.3. EPSS: 0.9% chance of exploitation in the next 30 days.

JSONata is a JSON query and transformation language. Prior to 1.8.8 and 2.2.1, crafted JSONata expressions could chain several object-integrity weaknesses to execute arbitrary code. The chain could overwrite $clone to mutate objects through evaluateTransformExpression, expose and deconstruct JSONata functions or lambdas through $merge.*, replace proc.arguments.forEach used by applyProcedure, and forge internal lambda state. These primitives allowed an attacker to reach prototype getters, prototype and constructor access, and process.getBuiltinModule with child_process, executing code with the privileges of the host process. This issue is fixed in versions 1.8.8 and 2.2.1.

Affected products

• Jsonata-Js Jsonata: before 1.8.8 (fixed in 1.8.8); from 2.0.0, before 2.2.1 (fixed in 2.2.1)

Published 2026-08-21. Last modified 2026-09-09.