CVE-2026-84942

High

Description

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.

SeverityHigh

CVSS8.7

Exploit probability—

ProductOpenSearch Dashboards

PublishedSep 8, 2026

First seenSep 8, 2026

Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

Patches

Vendor advisories

aws.amazon.com/security/security-bulletins/2026-102-aws/

Affected products

Product	Affected versions	Fixed in
OpenSearch OpenSearch Dashboards	v2.0.0 ≤ v ≤ v3.5.0	—

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