CVE-2026-102408 Inefficient Regular Expression Complexity in Elasticsearch Leading to Denial of Service
An authenticated user can cause denial of service in Elasticsearch by submitting complex regular expressions that trigger excessive CPU consumption.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-102408?
CVE-2026-102408 is a medium-severity denial of service vulnerability in Elastic Elasticsearch, published on 6 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-1333
Which versions are affected by CVE-2026-102408?
1 open source package ship an affected version, including elasticsearch. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
elasticsearch Bitnami | From 8.19.0 | 8.19.22, 9.4.8, 9.5.5 |
Products include Elastic Elasticsearch.
How do I fix CVE-2026-102408?
Upgrade elasticsearch to a fixed version for your release line: 8.19.22, 9.4.8 or 9.5.5.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-102408 being exploited?
There is no known exploitation of CVE-2026-102408 in the wild and no public exploit code.
Other vulnerabilities in Elastic Elasticsearch
- CVE-2015-1427 Elasticsearch Groovy Scripting Engine Remote Code Execution
- CVE-2014-3120 Elasticsearch Remote Code Execution
- CVE-2015-5377 Code injection in n/a
- CVE-2026-72649 Deserialization of Untrusted Data in Elasticsearch Leading to Remote Code Execution
- CVE-2026-72642 Use of Out-of-range Pointer Offset in the Elasticsearch Machine Learning Native Inference Process
Sources
Also known as BIT-elasticsearch-2026-102408, GHSA-43f3-46vj-x5jc, MINI-32g4-fx64-6wwf, MINI-6874-7fxh-xfh6, MINI-g3vg-27mr-jm3m, MINI-gjvj-gcf8-4r72 and 10 more.