Org.opensearch.plugin:opensearch security: OpenSearch has ineffective TLS certificate hostname verification
Affects org.opensearch.plugin:opensearch-securitySource GCVE Database
CVSS 2.2 Low : upgrade to 2.19.4.0 when convenient.
Data as of 27 Oct 2026, 00:07 UTC
- Patch
- Available – fixed in 2.19.4.0, 3.3.0.0
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:NWhat to do
Upgrade org.opensearch.plugin:opensearch-security to 2.19.4.0; org.opensearch.plugin:opensearch-security to 3.3.0.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Mavenorg.opensearch.plugin:opensearch-security | Affected
| Fixed in
|
| Mavenorg.opensearch.plugin:opensearch-security | Affected
| Fixed in
|
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Description
### 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.