CVE-2026-102408

Inefficient Regular Expression Complexity in Elasticsearch Leading to Denial of Service

MEDIUM
4.3
CVSS Score
Published: October 6, 2026 at 07:31 PM UTC
Updated: October 13, 2026 at 06:48 PM UTC
1 product affected across 1 vendorElasticsearch

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

95%
8.19.0 ≤ v < 8.19.229.1.0 ≤ v < 9.4.89.5.0 ≤ v < 9.5.58.19.09.1.09.4.09.5.0

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMelastic
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusANALYZED
CWE
CWE-1333

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