# Elasticsearch 8.19.20, 9.4.5 Security Update (ESA-2026-77) **URL:** \ **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-2026-77/389500 "2026-08-13T10:47:03Z")\ **Posts on this page:** 1\ **Page:** 1
**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-2026-77/389500/1 "2026-08-13T10:47:03Z")
**Inefficient Algorithmic Complexity in Elasticsearch Leading to Denial of Service** A flaw in Elasticsearch allows a low-privileged authenticated user who can index documents to submit a single small document containing a crafted user-supplied input. Processing one such document occupies a worker thread from a bounded pool for a disproportionate amount of time, degrading the availability of indexing operations on the affected node. **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 version 8.19.20 and 9.4.5. Versions 9.5.0 and later are not affected. **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 ( 4.3 ) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L **CVE ID:** CVE-2026-72685 **Problem Type:** CWE-407 - Inefficient Algorithmic Complexity