Quick answers
- Is CVE-2026-18420 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-18420 being exploited in the wild.
- How severe is CVE-2026-18420?
- High severity, with a CVSS score of 8.8, published 20 August 2026.
- Which products and versions are affected?
- OpenSearch Project OpenSearch Dashboards prior to 3.8.0.
- Is there a fix for CVE-2026-18420?
- A patch was published on 2026-09-01: Fixed in OpenSearch Dashboards 3.8.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-18420 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-18420?
- Check whether you run Amazon AWS or OpenSearch Project OpenSearch Dashboards at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a prototype pollution flaw in the TSVB plugin's metrics visualization API endpoint. The plugin fails to properly validate and sanitize JSON input before processing it, allowing an attacker to inject malicious properties that pollute the prototype chain and achieve arbitrary code execution on the server. The attack requires authentication to OpenSearch Dashboards and network access to the API endpoint. An authenticated attacker can craft a malicious JSON payload targeting the metrics visualization API to execute arbitrary code with the privileges of the OpenSearch process. The vulnerability was patched in OpenSearch Dashboards version 3.8.0 and later.
Affected products
- OpenSearch Project OpenSearch Dashboards prior to 3.8.0
Timeline
- 2026-08-20: disclosed
- 2026-09-01: patched: Fixed in OpenSearch Dashboards 3.8.0