# Elasticsearch 8.19.20, 9.4.5 Security Update (ESA-2026-133)

**URL:** <https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-security-update-esa-2026-133/389499>\
**Category:** Security Announcements\
**Created:** [August 13, 2026, 10:47am UTC](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-security-update-esa-2026-133/389499 "2026-08-13T10:47:00Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**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-security-update-esa-2026-133/389499/1 "2026-08-13T10:47:00Z")

</div>

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

**Description:**  
Uncontrolled Recursion (CWE-674) in the Elasticsearch wildcard matching helper can lead to a denial of service via Excessive Allocation (CAPEC-130). The matcher used to resolve wildcard patterns against names is implemented recursively and had no bound on recursion depth or on the total number of match operations performed. A search request containing a wildcard pattern with a large number of wildcard groups, evaluated against a sufficiently long name, exhausts the thread stack. Elasticsearch treats a stack overflow as an unrecoverable condition and shuts the node down, so the request terminates the affected node rather than failing gracefully.

**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

**Affected Configurations:**

> - All configurations are affected

**Solutions and Mitigations:**

The issue is resolved in versions 8.19.20 and 9.4.5.

**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-2026-72636  
**Problem Type:** CWE-674 - Uncontrolled Recursion  
**Impact:** CAPEC-130 - Excessive Allocation