CVE-2026-18420 - Remote Code Execution via Prototype Pollution in OpenSearch Dashboards TSVB Plugin

unknownCVE-2026-18420

Bulletin ID: 2026-085-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 08/20/2026 13:30 PM PDT Description: Improper input validation in the Time Series Visual Builder (TSVB) plugin in OpenSearch Dashboards before 3.8 allows a remote authenticated user with standard data access permissions to execute arbitrary code on the server by sending a crafted JSON payload to the metrics visualization API endpoint. To mitigate this issue, users should upgrade to OpenSearch Dashboards 3.8 or later. Impacted products and versions: - OpenSearch-Dashboards (open-source, self-managed): >=3.0.0, <3.8.0 - OpenSearch-Dashboards (AWS Managed): >=3.0.0, <3.8.0 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.

CSIRTS triage

vendor: OpenSearch product: OpenSearch Dashboards Remote code execution Code injectionaffected: >=3.0.0, <3.8.0

What: Improper input validation in Time Series Visual Builder (TSVB) plugin allows remote authenticated code execution via crafted JSON payload.
Who is affected: OpenSearch Dashboards users (self-managed and AWS-managed) on versions 3.0.0 through 3.7.x with standard data access permissions.
Urgency: Critical; authenticated RCE in widely-used visualization plugin requires immediate patching.
Action: Upgrade OpenSearch Dashboards to version 3.8.0 or later.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: AWS Security Bulletins (INTL · vendor-psirt · site)
Severity: unknown
Published: 2026-08-20
Exploitation: Not in CISA KEV at last sync

Original advisory: https://aws.amazon.com/security/security-bulletins/rss/2026-085-aws/

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-184200.96% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 58% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-18420	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

highCVE-2026-18420: Improper input validation in the Time Series Visual Builder (TSVB) plugin in OpenSearch Dashbo…nvd