CVE-2026-18420: Aws Amazon Opensearch Service

High severity, CVSS 8.8. EPSS: 0.7% chance of exploitation in the next 30 days.

Improper input validation in the Time Series Visual Builder (TSVB) plugin in OpenSearch Dashboards allows an authenticated remote user to execute arbitrary code on the server via a crafted JSON payload to the metrics visualization API endpoint. This issue is a form of prototype pollution that enables remote code execution.  To remediate this issue, users should upgrade to OpenSearch Dashboards 3.8 or later.

Affected products

• Aws Amazon Opensearch Service: from 3.0.0, before 3.8.0 (fixed in 3.8.0)
• Opensearch Opensearch Dashboards: from 3.0.0, before 3.8.0 (fixed in 3.8.0)

Published 2026-08-20. Last modified 2026-08-25.