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