# CVE-2026-72638: Uncontrolled Recursion in Elasticsearch Leading to Denial of Service

> An authenticated user with low privileges can cause a denial of service in Elasticsearch by submitting a malformed custom analysis definition that triggers uncontrolled recursion.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Aug 2026
- **Updated:** 13 Aug 2026
- **Also known as:** BIT-elasticsearch-2026-72638, CLEANSTART-2026-OO18479, CLEANSTART-2026-PP64708, GHSA-rx34-f5m9-h9p5, MINI-27p8-gpv6-pjfq, MINI-55rr-j72r-mf7r, MINI-5cgx-3j9w-688j, MINI-735p-9h7p-5gh4, MINI-7x7j-5cvr-6c3m, MINI-9q9x-p5jr-hhmm, MINI-c4mf-j8r6-jv9h, MINI-cp6r-4365-c372, MINI-fcqw-85hp-8vpx, MINI-fp23-hrmg-68mw, MINI-gjwp-7mj6-cvv4, MINI-m5m3-r75m-j9g8, MINI-mmmj-j66j-9ggf, MINI-p56g-7qfp-38xm, MINI-p5cv-wxr3-6m6q, MINI-p8w6-28gm-9x8r, MINI-q78w-gc67-hr58, MINI-qc3m-75hg-fc8x, MINI-rw58-7g32-9pvg, MINI-wm5m-648p-vf5m, MINI-wrc6-9cmq-qh8g, MINI-x85x-7342-xmwq

## What is CVE-2026-72638?

CVE-2026-72638 is a medium-severity denial of service vulnerability in Elastic Elasticsearch, published on 13 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to denial of service via Input Data Manipulation (CAPEC-153). An authenticated user holding only low-privileged index creation permissions can submit a single request containing a specially crafted, malformed custom analysis definition that is resolved recursively without a cycle or depth check, exhausting the thread stack and terminating the affected node.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-72638?

1 open source package ship an affected version, including elasticsearch. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `elasticsearch` | Bitnami | From 8.0.0 | 8.19.20, 9.4.5 |

Products: Elastic Elasticsearch.

## How do I fix CVE-2026-72638?

Upgrade elasticsearch to a fixed version for your release line: 8.19.20 or 9.4.5.

## Is CVE-2026-72638 being exploited?

There is no known exploitation of CVE-2026-72638 in the wild and no public exploit code.

## Other vulnerabilities in Elastic Elasticsearch

- [CVE-2015-1427](https://insights.sbomify.com/CVE-2015-1427/): Elasticsearch Groovy Scripting Engine Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2014-3120](https://insights.sbomify.com/CVE-2014-3120/): Elasticsearch Remote Code Execution (high 8.1, exploited in the wild)
- [CVE-2015-5377](https://insights.sbomify.com/CVE-2015-5377/): Code injection in n/a (critical 9.8)
- [CVE-2026-72649](https://insights.sbomify.com/CVE-2026-72649/): Deserialization of Untrusted Data in Elasticsearch Leading to Remote Code Execution (high 8.8)
- [CVE-2026-72642](https://insights.sbomify.com/CVE-2026-72642/): Use of Out-of-range Pointer Offset in the Elasticsearch Machine Learning Native Inference Process (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72638 and fix it if it is affected.

What it is: CVE-2026-72638 is a medium-severity denial of service vulnerability in Elastic Elasticsearch, published on 13 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72638 in the wild and no public exploit code.

Affected packages and fixed versions:
- elasticsearch (Bitnami): affected from 8.0.0; fixed in 8.19.20, 9.4.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72638/ (Markdown: https://insights.sbomify.com/CVE-2026-72638/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72638
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72638
- OSV: https://osv.dev/vulnerability/CVE-2026-72638

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72638/
Summaries are generated and may contain mistakes; the official description above is the record.