Cyber Resilience

CVE-2026-20139

DoS in Splunk 9.2.0 – 9.2.12

DoS
Published
18 February 2026
Modified
20 February 2026
Patch / advisory
View advisory
CVSS Score v3.1 4.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
EPSS Score 0.049 91th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-20139 is a medium-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Splunk Splunk. Its CVSS base score is 4.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Endpoint Denial of Service (T1499); ranked in the top 9% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-2 (Flaw Remediation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-400

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1499 Endpoint Denial of Service Impact
Adversaries may perform Endpoint Denial of Service (DoS) attacks to degrade or block the availability of services to users.
attack.mitre.org →
Why these techniques?

Authenticated low-priv user can abuse password-change REST endpoint to trigger resource exhaustion (CWE-400) resulting in application DoS on Splunk Web.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2024-45736Same product: Splunk Splunk
CVE-2023-40593Same product: Splunk Splunk
CVE-2023-40594Same product: Splunk Splunk
CVE-2025-20370Same product: Splunk Splunk
CVE-2024-36993Same product: Splunk Splunk
CVE-2023-32710Same product: Splunk Splunk
CVE-2023-22932Same product: Splunk Splunk
CVE-2024-45740Same product: Splunk Splunk
CVE-2025-20384Same product: Splunk Splunk
CVE-2024-36990Same product: Splunk Splunk

Affected Assets

splunk
splunk
9.2.0 — 9.2.12 · 9.3.0 — 9.3.9 · 9.4.0 — 9.4.8
splunk
splunk cloud platform
9.3.2411 — 9.3.2411.121 · 10.0.2503 — 10.0.2503.9 · 10.1.2507 — 10.1.2507.8

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SI-2 Flaw Remediation
  • AC-6 Least Privilege
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)

—

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match
prevent

Directly enforces validation and sanitization of user-supplied values in realname/tz/email before they reach the authentication/users endpoint, blocking the crafted payloads that trigger uncontrolled resource consumption.

SI-2 Flaw Remediation good match
prevent

Requires prompt application of the vendor patches that close the input-handling flaw in the listed Splunk versions, eliminating the root cause of the client-side DoS.

AC-6 Least Privilege partial match
prevent

Limits the ability of non-admin/power roles to invoke or influence the /authentication/users/username endpoint, reducing the attack surface available to low-privileged accounts.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.IR-04 mostly match
prevents

Explicitly requires monitoring and maintaining resource capacity, directly addressing uncontrolled consumption to preserve availability.

DE.CM-09 partial match
prevents

Continuous monitoring of computing resources can detect resource exhaustion but does not itself enforce allocation limits.

PR.IR-03 partial match
prevents

Resilience mechanisms such as avoiding single points of failure indirectly reduce impact of resource exhaustion.

PR.PS-01 partial match
prevents

Hardened configuration baselines can include resource quotas and limits that constrain consumption.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.16 Monitoring activities mostly match
detects

Resource-utilization monitoring and alerting on bottlenecks or overloads limits the impact of denial-of-service or resource-exhaustion attacks.

A.8.6 Capacity management mostly match
prevents

By continuously monitoring utilization, stress-testing peak loads, and maintaining documented plans to scale or throttle resources, the control directly limits an attacker’s ability to drive a system into uncontrolled resource exhaustion.

A.5.24 Information security incident management planning and preparation partial match
detects

Pre-agreed severity-based prioritization and resource allocation during incident triage reduce the likelihood that an attacker-induced resource exhaustion will overwhelm the organization before corrective action is taken.

A.5.29 Information security during disruption partial match
mitigates

Business-continuity plans that include resource-management controls reduce the likelihood that an attacker can trigger uncontrolled resource consumption by forcing the system into a degraded or fallback state.

A.5.30 ICT readiness for business continuity partial match
mitigates

Defining RTOs and capacity requirements for ICT services during business-impact analysis forces organizations to provision sufficient resources and throttling mechanisms, reducing the likelihood that an attacker can induce denial-of-service through uncontrolled resource consumption.

A.6.8 Information security event reporting partial match
detects

Early notification of anomalous resource consumption or system malfunctions enables throttling or isolation before availability is lost.

References