OpenSearch has ineffective TLS certificate hostname verification

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

2.2 · CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Description A regression was introduced in OpenSearch 2.18.0 that caused the plugins.security.ssl.transport.enforcehostnameverification 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.nodesdn to limit which certificates…

Published by the source

7 May 2026, 00:09 UTC

Last modified by the source

7 May 2026, 00:09 UTC

Source last checked

26 Oct 2026, 16:45 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-x5hg-x4gv-j98m

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# Patch Next advisory brief: GHSA-x5hg-x4gv-j98m

Advisory: OpenSearch has ineffective TLS certificate hostname verification
IDs: GHSA-x5hg-x4gv-j98m
Record: https://patchnext.com/advisories/ghsa-x5hg-x4gv-j98m (revision 1, source checked 26 Oct 2026, 16:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.opensearch.plugin:opensearch-security 3.3.0.0, 2.19.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.opensearch.plugin:opensearch-security: affected >= 2.18.0, < 2.19.4.0; >= 3.0.0, < 3.3.0.0; fixed in 2.19.4.0, 3.3.0.0

## Suggested inspection (read-only)
- Maven org.opensearch.plugin:opensearch-security: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.opensearch.plugin:opensearch-security.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-x5hg-x4gv-j98m (GitHub-reviewed advisory GHSA-x5hg-x4gv-j98m lists affected ranges: Maven org.opensearch.plugin:opensearch-security >=2.18.0 =3.0.0 <3.3.0.0)

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