CVE-2026-84942: Aws Amazon Opensearch Service

High severity, CVSS 8.7. EPSS: 0.5% chance of exploitation in the next 30 days.

Improper input validation in the Vega expression function implementation in OpenSearch Dashboards allows a remote authenticated actor with dashboard write permissions to execute arbitrary JavaScript in the context of other users' browser sessions by saving a crafted Vega visualization. The checkForFunctionProperty validation routine failed to recurse into arrays of objects, allowing a function property nested inside an array to bypass validation.

Affected products

• Aws Amazon Opensearch Service
• Opensearch Opensearch Dashboards: from v2.0.0, up to and including v3.5.0

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