# Elasticsearch 8.19.20, 9.4.5, 9.5.1 Security Update (ESA-2026-114)

**URL:** <https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-114/390087>\
**Category:** Security Announcements\
**Created:** [September 1, 2026, 6:44pm UTC](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-114/390087 "2026-09-01T18:44:39Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ismisepaul](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ismisepaul/32/102235_2.png) [@ismisepaul](https://discuss.elastic.co/u/ismisepaul)\
**Post date:** [September 1, 2026, 6:44pm UTC](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-114/390087/1 "2026-09-01T18:44:39Z")

</div>

**Deserialization of Untrusted Data in Elasticsearch Leading to Remote Code Execution**

Deserialization of Untrusted Data (CWE-502) in the Elasticsearch machine learning component can lead to remote code execution via Object Injection (CAPEC-586). A specially crafted trained model artifact could cause attacker-controlled logic to execute with a materially broader system-call surface than intended. Exploitation requires an authenticated user with sufficient privileges to create and deploy trained models.

**Affected Versions:**

> - 8.x: All versions from 8.0.0 up to and including 8.19.19
> - 9.x:

- All versions from 9.0.0 up to and including 9.4.4
- Version 9.5.0

**Affected Configurations:**

> - Exploitation requires an account that is authorized to create trained models, upload their definitions, and start a model deployment.
> - Clusters with no machine learning capacity, or where machine learning is disabled, are not affected.

**Solutions and Mitigations:**

The issue is resolved in Elasticsearch versions 8.19.20, 9.4.5, and 9.5.1.

**For Users that Cannot Upgrade:**

**Self-Managed**  
Disable machine learning cluster-wide by setting `xpack.ml.enabled: false` in `elasticsearch.yml` on all nodes and restarting the cluster. Third-party trained models should not be uploaded to a cluster running an affected version.

**Cloud**  
Machine learning capacity can be removed from Elastic Cloud Hosted deployments from the deployment configuration screen. Third-party trained models should not be uploaded to a deployment running an affected version.

**Indicators of Compromise (IOC)**

Review the trained models present in the cluster and their deployments. A trained model that your organization did not upload, or a model definition originating from an untrusted third-party source, is an indicator that this issue may have been exploited.

**Elastic Cloud Serverless**

Due to our continuous deployment and patching model, the vulnerability described in this security advisory was remediated in our Elastic Cloud Serverless offering before the public disclosure.

**Severity:** CVSSv3.1: High ( 8.8 ) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H  
**CVE ID:** CVE-2026-72649  
**Problem Type:** CWE-502 - Deserialization of Untrusted Data  
**Impact:** CAPEC-586 - Object Injection