# Elasticsearch 8.19.20, 9.4.5, 9.5.1 Security Update (ESA-2026-79)

**URL:** https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-79/389506
**Category:** Security Announcements
**Created:** [August 13, 2026, 10:47am UTC](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-79/389506 "2026-08-13T10:47:23Z")
**Posts on this page:** 1
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### Author: ![ikakavas](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ikakavas/32/34430_2.png) [@ikakavas](https://discuss.elastic.co/u/ikakavas)
#### Post date: [August 13, 2026, 10:47am UTC](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-79/389506/1 "2026-08-13T10:47:23Z")

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**Memory Allocation with Excessive Size Value in Elasticsearch Leading to Denial of Service**

A flaw in Elasticsearch allows a low-privileged authenticated user to submit a single small request containing a forged opaque identifier. Elasticsearch decodes and deserializes the identifier before confirming that it was legitimately issued by the cluster, and a size value carried inside the identifier drives an allocation that is neither capped nor accounted for by the available memory-usage controls. The resulting out-of-memory condition is fatal and terminates the affected node process, resulting in a denial of service.

**Affected Versions:**

> - All versions from 8.0.0 up to and including 8.19.19
> - All versions from 9.0.0 up to and including 9.4.4
> - Version 9.5.0

**Affected Configurations:**

> - All configurations are affected.

**Solutions and Mitigations:**

The issue is resolved in version 8.19.20, 9.4.5, and 9.5.1.

**For Users that Cannot Upgrade:**  
There are no workarounds for this vulnerability.

**Indicators of Compromise (IOC)**

There are no identified indicators of compromise for this issue.

**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: Medium ( 6.5 ) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H  
**CVE ID:** CVE-2026-72687  
**Problem Type:** CWE-789 - Memory Allocation with Excessive Size Value

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_[View the full topic](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-79/389506)._