OpenSearch has ineffective TLS certificate hostname verification
Description
A regression was introduced in OpenSearch 2.18.0 that caused the plugins.security.ssl.transport.enforce_hostname_verification setting to be ineffective. When this setting was enabled, OpenSearch did not verify that the hostname in a connecting node's TLS certificate matched the hostname of the connection. This could allow a node with a valid certificate (signed by the cluster's trusted CA) but an incorrect hostname SAN to join the cluster.
Impact
Clusters running affected versions with hostname verification enabled did not receive the expected protection from this setting. A node presenting a certificate signed by the cluster's trusted CA could join the cluster regardless of whether its hostname SAN matched. This regression does not affect certificate validation itself — only the additional hostname verification check.
Patches
This issue is fixed in OpenSearch 2.19.4 and 3.3.0.
Workarounds
Use more restrictive values for plugins.security.nodes_dn to limit which certificates are accepted for node-to-node communication.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.opensearch.plugin:opensearch-security | >= 2.18.0, < 2.19.4.0, >= 3.0.0, < 3.3.0.0 | 2.19.4.0, 3.3.0.0 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N- Weakness (CWE)
CWE-295- Platform
- Java / Kotlin (Maven)
- Package
org.opensearch.plugin:opensearch-security- Disclosed
- 07.05.2026
- Updated
- 11.10.2026 12:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-x5hg-x4gv-j98m - CC BY 4.0
Vulnerability history: org.opensearch.plugin:opensearch-security
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 14
- First → latest
- 08.2022 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 2
- Medium 9
- Low 3
Disclosures per year
- 2022: 1
- 2023: 7
- 2024: 0
- 2025: 2
- 2026: 4
-
OpenSearch has ineffective TLS certificate hostname verification this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.