# CVE-2026-84942: Stored Cross-Site Scripting via Vega Expression Function Bypass in OpenSearch Dashboards

> CVE-2026-84942: Stored Cross-Site Scripting via Vega Expression Function Bypass in OpenSearch Dashboards. CVSS 8.7 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-84942
Last updated: 2026-09-09T21:17:05Z

- Published: 2026-09-08 19:41 UTC · Updated: 2026-09-09 21:17 UTC · Assigner: AMZN
- CVSS: 8.7 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
- EPSS: 0.54%, 45th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-79

## 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.

## Affected vendors and products

- AWS: Amazon OpenSearch Service
- OpenSearch: OpenSearch Dashboards

## Tracked companies

- [Amazon Web Services](https://rewindex.com/company/aws.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-84942)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-84942)
- [https://aws.amazon.com/security/security-bulletins/2026-102-aws/](https://aws.amazon.com/security/security-bulletins/2026-102-aws/)
- [https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/2.19.5](https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/2.19.5)
- [https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/3.6.0](https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/3.6.0)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-84942 · Markdown: https://rewindex.com/cve/CVE-2026-84942.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-84942 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T04:05:41.538Z