# Elasticsearch 8.19.23, 9.4.8, 9.5.5 Security Update (ESA-2026-198)

**URL:** <https://discuss.elastic.co/t/elasticsearch-8-19-23-9-4-8-9-5-5-security-update-esa-2026-198/390872>\
**Category:** Security Announcements\
**Created:** [October 6, 2026, 6:52pm UTC](https://discuss.elastic.co/t/elasticsearch-8-19-23-9-4-8-9-5-5-security-update-esa-2026-198/390872 "2026-10-06T18:52:02Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![cronosda](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/cronosda/32/147882_2.png) [@cronosda](https://discuss.elastic.co/u/cronosda)\
**Post date:** [October 6, 2026, 6:52pm UTC](https://discuss.elastic.co/t/elasticsearch-8-19-23-9-4-8-9-5-5-security-update-esa-2026-198/390872/1 "2026-10-06T18:52:02Z")

</div>

**Uncontrolled Recursion in Elasticsearch Leading to Denial of Service**

Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to Denial of Service via a specially crafted request that causes the server to construct and process a deeply nested data structure with no bound on recursion depth.

Elasticsearch contains an uncontrolled recursion weakness in how it builds and serializes geometry values produced by scripted runtime fields. Unlike geometry supplied as text, which is subject to a nesting-depth limit, geometry constructed from a script's output is not bounded. An authenticated user with read access to a single index can submit a request defining such a field with a script that produces a deeply nested structure. Processing this request recurses past the available stack space, causing the affected node to terminate. The node does not recover automatically on all deployments and may require manual intervention to restore service.

**Affected Versions:**

> - 8.x: All versions from 8.12.0 up to and including 8.19.22
> - 9.x:

- All versions from 9.0.0 up to and including 9.4.7
- All versions from 9.5.0 up to and including 9.5.4

**Affected Configurations:**

> - All configurations are affected.

**Solutions and Mitigations:**

The issue is resolved in versions 8.19.23, 9.4.8, and 9.5.5.

The versions above are the first releases verified to contain the fix. Elastic recommends upgrading to one of these fixed versions or a later release verified to contain the fix, and reviewing the known issues for your target version before upgrading.

**For Users that Cannot Upgrade:**

> - There are no workarounds for this vulnerability.

**Indicators of Compromise (IOC)**

No specific indicators of compromise have been identified for this vulnerability.

**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-2026-103008  
**Problem Type:** CWE-674 - Uncontrolled Recursion