# CVE-2026-102408: Inefficient Regular Expression Complexity in Elasticsearch Leading to Denial of Service

> CVE-2026-102408: Inefficient Regular Expression Complexity in Elasticsearch Leading to Denial of Service. CVSS 4.3 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-102408
Last updated: 2026-10-13T18:48:04Z

- Published: 2026-10-06 19:31 UTC · Updated: 2026-10-13 18:48 UTC · Assigner: elastic
- CVSS: 4.3 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
- EPSS: 0.35%, 28th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-1333

## 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.

## Affected vendors and products

- Elastic: Elasticsearch

## Tracked companies

- [Elastic Cloud](https://rewindex.com/company/elastic-cloud.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-102408)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-102408)
- [https://discuss.elastic.co/t/elasticsearch-8-19-22-9-4-8-and-9-5-5-security-update-esa-2026-189/390862](https://discuss.elastic.co/t/elasticsearch-8-19-22-9-4-8-and-9-5-5-security-update-esa-2026-189/390862)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-102408 · Markdown: https://rewindex.com/cve/CVE-2026-102408.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-102408 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:05:07.977Z