CVE-2026-18420

HIGHPre-NVD 8.88.8
EchelonGraph scoreLOW confidence

This high-severity CVE scores 8.8 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: cna:amzn
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: CVSS: 8.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
8.8
EG Score
8.8(low)
EG Risk
44(Track)
EG Risk 44/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
EPSS %ILE
KEV
Not listed

Published

August 20, 2026

Last Modified

August 20, 2026

Advisory Details (2)

Auto-updated Aug 20, 2026
Patch available. Sources: github.
generic

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

https://aws.amazon.com/security/security-bulletins/2026-085-aws/
github Patch Available

Remote Code Execution via Prototype Pollution in OpenSearch Dashboards TSVB Plugin · Advisory · opensearch-project/OpenSearch-Dashboards · GitHub

https://github.com/opensearch-project/OpenSearch-Dashboards/security/advisories/GHSA-xmqx-xq2p-8jq2

Vendor Advisories for CVE-2026-18420(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 2× in last 7d / 2× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-20 20:57 UTCEG score recompute
  2. 2026-08-20 20:56 UTCMITRE cvelistV5first tracked

Frequently asked(4)

What is CVE-2026-18420?
CVE-2026-18420 is a high vulnerability published on August 20, 2026. 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…
When was CVE-2026-18420 disclosed?
CVE-2026-18420 was first published in the National Vulnerability Database on August 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-18420?
CVE-2026-18420 has a CVSS v4.0 base score of 8.8 (CNA self-assessment; NVD's own analysis pending). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-18420?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-18420, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-18420

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