CVE WatchOct 13, 2026

CVE-2026-102408

Inefficient Regular Expression Complexity (CWE-1333) in Elasticsearch can lead to denial of service via Regular Expression Exponential Blowu

CVSS

4.3

Medium

EPSS

0.3%

p27

KEV

—

Exploit Today

0-100

Published: Oct 6, 2026 · Last modified: Oct 13, 2026 · CWE-1333

EPSS · 30d

0.3%EPSS · 30 days0.3%

2026-10-072026-10-22

Technical 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.

Official references

discuss.elastic.cohttps://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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