---
id: CVE-2026-84942
title: >-
  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…
summary: >-
  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…
severity: high
cvss: 8.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N'
cwe:
  - CWE-79
vendor: AWS
product: Amazon OpenSearch Service
affected:
  - amazon_opensearch_service
  - dashboards >= v2.0.0 <= v3.5.0
published: '2026-09-08'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:17:05.473'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84942'
references:
  - url: 'https://aws.amazon.com/security/security-bulletins/2026-102-aws/'
    label: ff89ba41-3aa1-4d27-914a-91399e9639e5
  - url: >-
      https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/2.19.5
    label: ff89ba41-3aa1-4d27-914a-91399e9639e5
  - url: >-
      https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/3.6.0
    label: ff89ba41-3aa1-4d27-914a-91399e9639e5
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-09T20:45:08.722192Z'
epss: 0.00544
epssPercentile: 0.43296
ingestedAt: '2026-09-08T20:10:03.220Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.