Uncontrolled Recursion in Elasticsearch Leading to Denial of Service (CVE-2026-72638)
Description
CVE-2026-72638 is a medium severity vulnerability in Elasticsearch where uncontrolled recursion in processing custom analysis definitions can cause denial of service. An authenticated user with low-privileged index creation permissions can submit a specially crafted request that triggers recursive resolution without cycle or depth checks. This exhausts the thread stack and crashes the affected node. The issue affects Elasticsearch versions from 8.0.0 up to but not including 8.19.20, and from 9.0.0 up to but not including 9.4.5. A patch is available to address this vulnerability.
Affected software
pkg:bitnami/elasticsearchRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves uncontrolled recursion (CWE-674) in Elasticsearch's handling of custom analysis definitions. An authenticated user with minimal privileges can craft a malformed analysis definition that causes recursive resolution without safeguards against cycles or excessive depth. This leads to stack exhaustion and node termination, resulting in denial of service. The vulnerability affects Elasticsearch versions >=8.0.0 <8.19.20 and >=9.0.0 <9.4.5. No known exploits are reported in the wild. A patch is available to fix the issue.
Potential Impact
Successful exploitation results in denial of service by exhausting the thread stack and terminating the affected Elasticsearch node. This can disrupt availability of the service. The attacker requires authenticated access with low-privileged index creation permissions, limiting the scope of potential attackers.
Mitigation Recommendations
A patch is available for this vulnerability. Users should upgrade affected Elasticsearch versions to 8.19.20 or later, or 9.4.5 or later, where the issue is fixed. No additional mitigation steps are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- BIT-elasticsearch-2026-72638
- Osv Schema Version
- 1.6.2
- Aliases
- ["CVE-2026-72638"]
- Ecosystems
- ["Bitnami"]
- Database Specific Severity
- Medium
- State
- PUBLISHED
Threat ID: 6a85b4b2acd9273b492514c9
Added to database: 08/19/2026, 13:50:42 UTC
Last enriched: 08/19/2026, 14:12:41 UTC
Last updated: 10/04/2026, 10:04:22 UTC
Views: 70
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