# 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.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Oct 2026
- **Updated:** 6 Oct 2026
- **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, MINI-j5wr-85ww-qrqc, MINI-mf2f-975f-g5qv, MINI-mpjj-686v-v64r, MINI-pf33-rmwh-r5hw, MINI-q695-prr7-955r, MINI-rm2r-8h23-53c2, MINI-vp65-qrx6-r833, MINI-wgpx-rcqv-f54m, MINI-wqwv-cwp9-6mw3, MINI-x2jf-5x96-wxgx

## 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 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2026-102408?

1 open source package ship an affected version, including elasticsearch. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `elasticsearch` | Bitnami | From 8.19.0 | 8.19.22, 9.4.8, 9.5.5 |

Products: 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.

## 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](https://insights.sbomify.com/CVE-2015-1427/): Elasticsearch Groovy Scripting Engine Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2014-3120](https://insights.sbomify.com/CVE-2014-3120/): Elasticsearch Remote Code Execution (high 8.1, exploited in the wild)
- [CVE-2015-5377](https://insights.sbomify.com/CVE-2015-5377/): Code injection in n/a (critical 9.8)
- [CVE-2026-72649](https://insights.sbomify.com/CVE-2026-72649/): Deserialization of Untrusted Data in Elasticsearch Leading to Remote Code Execution (high 8.8)
- [CVE-2026-72642](https://insights.sbomify.com/CVE-2026-72642/): Use of Out-of-range Pointer Offset in the Elasticsearch Machine Learning Native Inference Process (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-102408 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-102408 in the wild and no public exploit code.

Affected packages and fixed versions:
- elasticsearch (Bitnami): affected from 8.19.0; fixed in 8.19.22, 9.4.8, 9.5.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-102408/ (Markdown: https://insights.sbomify.com/CVE-2026-102408/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-102408
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-102408
- OSV: https://osv.dev/vulnerability/CVE-2026-102408

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-102408/
Summaries are generated and may contain mistakes; the official description above is the record.