# Elasticsearch 8.19.19, 9.3.8, 9.4.4 Security Update (ESA-2026-64)

**URL:** <https://discuss.elastic.co/t/elasticsearch-8-19-19-9-3-8-9-4-4-security-update-esa-2026-64/388565>\
**Category:** Security Announcements\
**Created:** [July 21, 2026, 9:01pm UTC](https://discuss.elastic.co/t/elasticsearch-8-19-19-9-3-8-9-4-4-security-update-esa-2026-64/388565 "2026-07-21T21:01:02Z")\
**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:** [July 21, 2026, 9:01pm UTC](https://discuss.elastic.co/t/elasticsearch-8-19-19-9-3-8-9-4-4-security-update-esa-2026-64/388565/1 "2026-07-21T21:01:02Z")

</div>

**Reachable Assertion in Elasticsearch Leading to Denial of Service**

Reachable Assertion (CWE-617) in Elasticsearch can lead to denial of service via Input Data Manipulation (CAPEC-153). A specially crafted search request containing a null value in a specific query clause causes an internal assertion to be raised during query parsing. Because Elasticsearch treats assertion failures as fatal errors, this terminates the affected node process. A low-privileged authenticated user with read access to at least one index can exploit this condition with a single request to cause a node to terminate, disrupting search availability. In a single-node deployment this fully stops Elasticsearch; in a multi-node cluster it reduces cluster capacity for each affected node.

**Affected Versions:**

- 8.x: All versions from 8.0.0 up to and including 8.19.18
- 9.x:
  - All versions from 9.0.0 up to and including 9.3.7
  - All versions from 9.4.0 up to and including 9.4.3

Users on the 9.5.x release line are not affected. The fix was incorporated into 9.5.0 before its initial release.

**Affected Configurations:**

- All configurations of Elasticsearch are affected. Exploitation requires an authenticated user with at least read access to one index; no elevated administrative privileges are needed.

**Solutions and Mitigations:**

The issue is resolved in versions 8.19.19, 9.3.8, and 9.4.4.

**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-2026-63140  
**Problem Type:** CWE-617 - Reachable Assertion  
**Impact** : CAPEC-153 - Input Data Manipulation