CVE-2026-18420

RCE via Prototype Pollution in OpenSearch Dashboards

HIGH
8.8
CVSS Score
Published: August 20, 2026 at 08:40 PM UTC
Updated: October 26, 2026 at 10:10 AM UTC
2 products affected across 2 vendorsOpenSearch DashboardsAmazon OpenSearch Service

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Severity
HIGH8.8
Exploit prediction
EPSS 1.0%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.0.0 ≤ v < 3.8.03.0.0
Affected range stops below 3.8.0, so it looks safe — our inference, not a vendor statement
3.0.0 ≤ v < 3.8.03.0.0
Affected range stops below 3.8.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.8HIGHAMZN
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-1321

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