# Elasticsearch 8.19.20, 9.4.5, 9.5.1 Security Update (ESA-2026-118)

**URL:** <https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-118/389497>\
**Category:** Security Announcements\
**Created:** [August 13, 2026, 10:46am UTC](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-118/389497 "2026-08-13T10:46:53Z")\
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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, 10:46am UTC](https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-9-5-1-security-update-esa-2026-118/389497/1 "2026-08-13T10:46:53Z")

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

Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to denial of service via Serialized Data with Nested Payloads (CAPEC-230). An authenticated user holding only read privileges on a single index can submit one specially crafted search request whose deeply nested structure is processed without a depth limit, exhausting the thread stack and terminating the affected node.

**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:**

All configurations are affected. The retriever framework of the search API is available by default; exploitation requires only read access to a single index.

**Solutions and Mitigations:**

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

**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-2026-72647  
**Problem Type:** CWE-674 - Uncontrolled Recursion  
**Impact:** CAPEC-230 - Serialized Data with Nested Payloads

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Change log

- Previously 9.5.1 was mentioned in the title only, but not in the solutions and mitigations. Also it never stated that 9.5.0 was affected.

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