High severity · published Aug 20, 2026
CVE-2026-18420
RCE via Prototype Pollution in OpenSearch Dashboards
8.8
CVSS
1%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.0% · higher than 61% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AO
Amazon OpenSearch Service · AWS
3.0.0 before 3.8.0 · source: vendor
OD
OpenSearch Dashboards · OpenSearch
3.0.0 before 3.8.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-18420
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-18420
aws.amazon.com
https://aws.amazon.com/security/security-bulletins/2026-085-aws/
github.com
https://github.com/opensearch-project/OpenSearch-Dashboards/releases/tag/3.8.0
github.com
https://github.com/opensearch-project/OpenSearch-Dashboards/security/advisories/GHSA-xmqx-xq2p-8jq2
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