Client-Side Denial of Service (DoS) through ''/splunkd/__raw/services/authentication/users/username'' REST API endpoint in Splunk Enterprise

Advisory ID: SVD-2026-0204

CVE ID: CVE-2026-20139

Published: 2026-02-18

Last Update: 2026-02-18

CVSSv3.1 Score: 4.3, Medium

CVSSv3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CWE: CWE-400

Bug ID: VULN-30996

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.

Solution

Upgrade Splunk Enterprise to versions 10.2.0, 10.0.2, 9.4.8, 9.3.9, 9.2.12, or higher.

Splunk is actively monitoring and patching Splunk Cloud Platform instances.

Product Status

ProductBase VersionComponentAffected VersionFix Version
Splunk Enterprise10.2Splunk WebNot affected10.2.0
Splunk Enterprise10.0Splunk Web10.0.0 to 10.0.110.0.2
Splunk Enterprise9.4Splunk Web9.4.0 to 9.4.79.4.8
Splunk Enterprise9.3Splunk Web9.3.0 to 9.3.89.3.9
Splunk Enterprise9.2Splunk Web9.2.0 to 9.2.119.2.12
Splunk Cloud Platform10.2.2510Splunk WebBelow 10.2.2510.310.2.2510.3
Splunk Cloud Platform10.1.2507Splunk WebBelow 10.1.2507.810.1.2507.8
Splunk Cloud Platform10.0.2503Splunk WebBelow 10.0.2503.910.0.2503.9
Splunk Cloud Platform9.3.2411Splunk WebBelow 9.3.2411.1219.3.2411.121

Mitigations and Workarounds

The vulnerability affects instances with Splunk Web turned on, turning Splunk Web off is a possible workaround. See Disable unnecessary Splunk Enterprise components and the web.conf configuration specification file for more information on turning off Splunk Web.

Detections

None

Severity

Splunk rates this vulnerability a 4.3, Medium, with a CVSSv3.1 vector of CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.

Acknowledgments

STÖK / Fredrik Alexandersson