# CVE-2026-18420

## Summary

- **CVE ID:** CVE-2026-18420
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-1321
- **Published:** Aug 20, 2026
- **Last Modified:** Aug 25, 2026

## Description

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 (3.0.0)
- OpenSearch — OpenSearch Dashboards (3.0.0)

## References

- [CNA](https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/3.8.0)
- [CNA](https://github.com/opensearch-project/OpenSearch-Dashboards/security/advisories/GHSA-xmqx-xq2p-8jq2)
- [CNA](https://aws.amazon.com/security/security-bulletins/2026-085-aws/)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.66%
- **EPSS Percentile:** 49.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._