# CVE-2026-20139: Denial of service in Splunk Cloud Platform

> A low-privileged user can cause client-side denial of service in Splunk Web by crafting malicious payloads in user profile parameters.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Feb 2026
- **Updated:** 19 Feb 2026
- **Also known as:** GHSA-4vmx-r9fj-4cm5

## What is CVE-2026-20139?

CVE-2026-20139 is a medium-severity denial of service vulnerability in Splunk Splunk, published on 18 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

In Splunk Enterprise versions below 10.2.0, 10.0.2, 9.4.8, 9.3.9, and 9.2.12, and Splunk Cloud Platform versions below 10.2.2510.3, 10.1.2507.8, 10.0.2503.9, and 9.3.2411.121, a low-privileged user that does not hold the "admin" or "power" Splunk roles could craft a malicious payload into the `realname`, `tz`, or `email` parameters of the `/splunkd/__raw/services/authentication/users/username` REST API endpoint when they change a password. This could potentially lead to a client‑side denial‑of‑service (DoS). The malicious payload might significantly slow page load times or render Splunk Web temporarily unresponsive.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-20139?

It affects 2 products.


Products: Splunk Splunk, Splunk Splunk Cloud Platform.

## How do I fix CVE-2026-20139?

No fix has been published for CVE-2026-20139 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-20139 being exploited?

There is no known exploitation of CVE-2026-20139 in the wild and no public exploit code.

## Other vulnerabilities in Splunk Splunk

- [CVE-2026-20253](https://insights.sbomify.com/CVE-2026-20253/): Splunk Enterprise Missing Authentication for Critical Function (critical 9.8, exploited in the wild)
- [CVE-2026-76268](https://insights.sbomify.com/CVE-2026-76268/): Missing Authentication for Critical Function in the Patroni REST API in Splunk Enterprise (critical 9.8)
- [CVE-2026-76284](https://insights.sbomify.com/CVE-2026-76284/): Improper Neutralization in Splunk Enterprise (critical 9.8)
- [CVE-2026-76285](https://insights.sbomify.com/CVE-2026-76285/): Improper Adherence to Coding Standards in Splunk Enterprise (critical 9.8)
- [CVE-2017-17067](https://insights.sbomify.com/CVE-2017-17067/): Auth bypass in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20139 and fix it if it is affected.

What it is: CVE-2026-20139 is a medium-severity denial of service vulnerability in Splunk Splunk, published on 18 Feb 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-2026-20139 in the wild and no public exploit code.

Affected product: Splunk Splunk. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-20139/ (Markdown: https://insights.sbomify.com/CVE-2026-20139/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20139
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20139
- OSV: https://osv.dev/vulnerability/CVE-2026-20139

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20139/
Summaries are generated and may contain mistakes; the official description above is the record.