Splunk Enterprise Unauthenticated Arbitrary File Operations/RCE (CVE-2026-20253): Overview and Takeaways

Splunk disclosed CVE-2026-20253 on June 10, 2026, affecting Splunk Enterprise versions in the 10.0.x and 10.2.x branches. The flaw stems from a PostgreSQL sidecar service endpoint that completely lacks authentication controls (CWE-306), allowing any network-reachable attacker to invoke arbitrary file creation or truncation operations without credentials. Researchers have demonstrated that this file-write primitive can be chained into remote code execution by abusing PostgreSQL’s lo_export function to write and subsequently execute malicious scripts on the Splunk server. No active exploitation in the wild has been reported at time of writing; however, a public proof-of-concept is available on GitHub, making exploitation attempts a near-term probability for any internet-exposed or inadequately segmented Splunk deployment. 

What do I need to know? 

• CVE: CVE-2026-20253 
• Severity: 9.8 (Critical) — CVSSv3.1 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), per Splunk vendor advisory 
• Attack Vector: Network — unauthenticated, no user interaction required 
• Root Cause: Missing Authentication for Critical Function (CWE-306); the PostgreSQL sidecar service endpoint performs no credential verification, allowing any network-reachable user to invoke file operations without credentials 
• Impact:  
  • Unauthenticated arbitrary file creation and truncation on the Splunk server filesystem 
  • Remote code execution via PostgreSQL lo_export abuse and malicious database restoration 
  • Service disruption through destruction or corruption of critical database files 
  • Potential lateral movement from a compromised Splunk server into monitored environments 

Products and Systems Affected 

• Splunk Enterprise 10.2.x: Versions 10.2.0–10.2.3 affected → Fixed in 10.2.4 
• Splunk Enterprise 10.0.x: Versions 10.0.0–10.0.6 affected → Fixed in 10.0.7 
• Splunk Enterprise 10.4.x: Not affected — 10.4.0 is the baseline fixed version 
• Splunk Cloud Platform: Not affected — does not use PostgreSQL sidecars 

What do I need to do? 

Review and Audit

• Splunk Cloud instances are not affected and do not require action for this CVE. 
• Review Splunk server logs for unexpected access to the PostgreSQL sidecar service endpoint, anomalous file creation activity, or unexpected database backup/restore operations — these may indicate exploitation attempts. 
• Monitor for unexpected process execution from within the Splunk service context, particularly Python script execution not initiated by a known user or scheduled search. 
• Splunk has not published indicators of compromise; detection relies on log review, file system auditing, and process monitoring. 

Patch Immediately 

• Splunk Enterprise 10.2.x: Upgrade to 10.2.4 or later. 
• Splunk Enterprise 10.0.x: Upgrade to 10.0.7 or later. 
• Splunk Enterprise 10.4.x: Version 10.4.0 is not affected; no action is required for this CVE. 
• Refer to the Splunk vendor advisory (SVD-2026-0603) for full patch guidance. 
• Note: Splunk has stated no mitigations or workarounds exist – patching is the only remediation. 

Mitigation (If Patching Is Delayed) 

• Restrict network access to Splunk management interfaces and the PostgreSQL sidecar service to trusted IP ranges only. The PostgreSQL sidecar endpoint must not be reachable from untrusted networks or the public internet. 
• Implement network segmentation to isolate Splunk infrastructure from broader enterprise environments, limiting blast radius if exploitation occurs. 
• Monitor filesystem activity on Splunk servers for unauthorized file creation, particularly in directories accessible to the Splunk service account. 
• Treat any internet-facing or insufficiently network-segmented Splunk Enterprise instance running an affected version as high risk for exploitation until the patch is applied, given the availability of a public proof of concept. 

NetSPI Product and Services Coverage 

NetSPI’s External Attack Surface Management has released a detection for this CVE. The current detection name is: Vulnerable Version – Splunk Enterprise – Arbitrary File Operations (CVE-2026-20253) 

NetSPI’s Penetration Testing Services can also help identify exposure to these vulnerabilities. 

Additional Resources 

• NVD — CVE-2026-20253 
• MITRE — CVE-2026-20253 
• Splunk Security Advisory — SVD-2026-0603 
• Splunk Enterprise 10.2.4 Release Notes 
• Splunk Enterprise 10.0.7 Release Notes