Inefficient regex complexity in Elasticsearch enables denial of service
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Deferred Red Hat: fix deferred
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-1333.
Summary
Elastic Elasticsearch versions 8.19.0 through 8.19.21, 9.1.0 through 9.3.8, 9.4.0 through 9.4.7 and 9.5.0 through 9.5.4 are affected. The ES|QL CHUNK function accepts user-supplied regular expressions as text separators without checking their complexity or bounding their execution time (CWE-1333). An authenticated user with read access to a text-based index can cause catastrophic backtracking with a crafted regular expression, consuming CPU and degrading query throughput on the node.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Elastic | Elasticsearch | 8.19.0 – 8.19.21; 9.1.0 – 9.3.8; 9.4.0 – 9.4.7; 9.5.0 – 9.5.4 | — | No fix listed | CNA |
- Elasticsearch VendorElastic Affected 8.19.0 – 8.19.21; 9.1.0 – 9.3.8; 9.4.0 – 9.4.7; 9.5.0 – 9.5.4 Fixed in — No fix listed CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:elastic:elasticsearch:*:*:*:*:*:*:*:* | 8.19.0 to before 8.19.22; 9.1.0 to before 9.4.8; 9.5.0 to before 9.5.5 | Vulnerable | Elastic |
- cpe:2.3:a:elastic:elasticsearch:*:*:*:*:*:*:*:* Versions 8.19.0 to before 8.19.22; 9.1.0 to before 9.4.8; 9.5.0 to before 9.5.5 Vulnerable ·Elastic
Remediation
The sources list no fixed version for Elasticsearch. Red Hat rates this Moderate and lists Red Hat OpenShift AI (RHOAI) as affected, with no available plan for a fix.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
Not affected: 1 product
- Red Hat Quay 3
Timeline
- 2026-10-06 Threatist record created from CVE-2026-102408
- 2026-10-07 CISA SSVC decision points changed
- 2026-10-07 Alias added: GHSA-43f3-46vj-x5jc
- 2026-10-07 Affected versions changed · Red Hat
- 2026-10-07 CVSS score added · Red Hat
- 2026-10-08 Affected versions changed · Red Hat
References
More Elasticsearch vulnerabilities
- TI-2015-01295 The Groovy scripting engine in Elasticsearch before 1.3.8 and 1.4.x before 1.4.3 allows… KEVCVSS 3.1CRITICAL 9.8
- TI-2014-02491 The default configuration in Elasticsearch before 1.2 enables dynamic scripting, which… KEVCVSS 3.1HIGH 8.1
- TI-2023-15037 Elasticsearch StackOverflow vulnerability CVSS 3.1HIGH 7.5
- TI-2021-05135 Information disclosure in Elasticsearch CVSS 3.1MEDIUM 6.5
- TI-2021-05136 All versions of Elastic Cloud Enterprise has the Elasticsearch “anonymous” user enabled… CVSS 3.1HIGH 7.5
- TI-2015-04530 Elasticsearch before 1.6.1 allows remote attackers to execute arbitrary code via… CVSS 3.0CRITICAL 9.8
Sources
- CVE-2026-102408 · CVE Program
- CVE-2026-102408 · NVD
- FIRST EPSS
- GHSA-43f3-46vj-x5jc · GitHub Advisory Database · CC BY 4.0
- CVE-2026-102408 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences