CVE-2026-18420 RCE via Prototype Pollution in OpenSearch Dashboards
Authenticated attackers can execute arbitrary code on OpenSearch Dashboards servers via prototype pollution in the TSVB plugin.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-18420?
CVE-2026-18420 is a high-severity code injection vulnerability in AWS Amazon OpenSearch Service, published on 20 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-1321
Which versions are affected by CVE-2026-18420?
How do I fix CVE-2026-18420?
No fix has been published for CVE-2026-18420 yet. Limit exposure of the affected software until one is available.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-18420 being exploited?
There is no known exploitation of CVE-2026-18420 in the wild and no public exploit code.
Sources
Also known as GHSA-jhcc-gw3q-f4pc, GHSA-xmqx-xq2p-8jq2.