Cyber Resilience

CVE-2026-20251

RCE in Splunk 9.3.0 – 9.3.13

RCEDeserialization
Published
10 June 2026
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.19 97th percentile
Risk Priority 76 floored blend · peak EPSS

Summary

CVE-2026-20251 is a high-severity Deserialization of Untrusted Data (CWE-502) vulnerability in Splunk Splunk. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 3% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A08:2025 Software or Data Integrity Failures

EU & UK References

Vulnerability Data

In Splunk Enterprise versions below 10.2.4, 10.0.7, 9.4.12, and 9.3.13, Splunk Cloud Platform versions below 10.3.2512.12, 10.2.2510.14, 10.1.2507.22, and 9.3.2411.132, and Splunk Secure Gateway versions below 3.10.6, 3.9.20, and 3.8.67, a low-privileged user that does not hold the 'admin' or…

more

'power' Splunk roles could perform a Remote Code Execution (RCE) through the Splunk Secure Gateway app.<br><br>The Remote Code Execution is possible because of unsafe deserialization of App Key Value Store (KV Store) data through the ‘jsonpickle’ Python library, which reconstructs arbitrary Python objects from specially crafted JavaScript Object Notation (JSON) without adequate validation.

CWE(s)
CWE-502

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-40595Same product: Splunk Splunk
CVE-2024-36984Same product: Splunk Splunk
CVE-2025-20389Same product: Splunk Splunk
CVE-2025-20383Same product: Splunk Splunk
CVE-2026-20240Same product: Splunk Splunk
CVE-2026-20254Same product: Splunk Splunk
CVE-2023-22934Same product: Splunk Splunk
CVE-2026-20257Same product: Splunk Splunk
CVE-2026-20256Same product: Splunk Splunk
CVE-2025-20227Same product: Splunk Splunk

Affected Assets

splunk
splunk
9.3.0 — 9.3.13 · 9.4.0 — 9.4.12 · 10.0.0 — 10.0.7
splunk
splunk cloud platform
9.3.2411 — 9.3.2411.132 · 10.1.2507 — 10.1.2507.22 · 10.2.2510 — 10.2.2510.14
splunk
splunk secure gateway
3.8.0 — 3.8.67 · 3.9.0 — 3.9.20 · 3.10.0 — 3.10.6

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can uncover deserialization flaws before deployment.

SI-10 Information Input Validation good match

Input validation directly stops deserialization of untrusted data by ensuring inputs are valid before processing.

SA-8 Security and Privacy Engineering Principles partial match

Engineering principles such as safe deserialization and input sanitization structurally prevent the weakness from being introduced.

SI-7 Software, Firmware, and Information Integrity partial match

Integrity verification tools can detect malformed or tampered serialized data after the fact.

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.PS-02 none match
prevents

PR.PS-02 addresses only post-deployment updates/patching and cannot prevent introduction of unsafe deserialization code, yet it can remediate some instances when the flaw exists in outdated libraries or components.

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing includes validation of deserialization routines and the use of untrusted data, reducing the likelihood that unsafe object reconstruction will be deployed.

A.8.28 Secure coding partial match
prevents

Requiring vetted libraries, regular updates and SAST before release reduces the likelihood that deserialization logic will accept and act on attacker-controlled serialized objects.

A.8.8 Management of technical vulnerabilities partial match
finds

Regular scanning of third-party libraries and timely patching reduce the likelihood that unsafe deserialization vulnerabilities remain active.

A.8.7 Protection against malware none match
none

Mandatory malware scanning of data received over networks or storage media intercepts malicious serialized payloads before they are deserialized by the target application.

References