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