CVE-2026-102408: CWE-1333 Inefficient Regular Expression Complexity in Elastic Elasticsearch
Description
Inefficient Regular Expression Complexity (CWE-1333) in Elasticsearch can lead to denial of service via Regular Expression Exponential Blowup (CAPEC-492). The ES|QL CHUNK function's recursive chunking strategy accepts a list of user-supplied regular expressions used as text-splitting separators, without validating their computational complexity or bounding their execution time. An authenticated user with read access to any text-based index can submit a specially crafted regular expression that triggers catastrophic backtracking, consuming excessive CPU on Elasticsearch worker threads and degrading query throughput for other tenants on the affected node. The cluster does not crash as a result of this issue.
CVSS v3.1
Score 4.3medium
Affected software
Elastic
Elasticsearch
pkg:maven/org.elasticsearch/elasticsearchRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CWE-1333) in Elasticsearch's ES|QL CHUNK function allows an authenticated user with read access to supply complex regular expressions that trigger exponential blowup in regex processing. The recursive chunking strategy does not limit the computational complexity or execution time of these regexes, resulting in catastrophic backtracking. This causes excessive CPU usage on Elasticsearch worker threads, degrading query performance for other tenants sharing the node. The issue leads to denial of service conditions by resource exhaustion but does not crash the cluster.
Potential Impact
The vulnerability can cause denial of service through resource exhaustion by excessive CPU consumption on Elasticsearch worker threads. This degrades query throughput for other tenants on the affected node but does not cause cluster crashes or data loss. The impact is limited to availability degradation under attack conditions by authenticated users with read access.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch links or official fixes are provided, users should monitor Elastic's advisories for updates. In the meantime, restrict read access to trusted users and consider limiting the use of complex regular expressions in ES|QL CHUNK queries if possible.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- elastic
- Date Reserved
- 2026-09-29T02:06:02.426Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ac550e02cdf04f656d8a13b
Added to database: 10/06/2026, 19:49:52 UTC
Last enriched: 10/06/2026, 20:04:23 UTC
Last updated: 10/06/2026, 20:28:11 UTC
Views: 7
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