6 min read
By: RedLegg's Cyber Threat Intelligence Team
About:
CVE-2026-20253 is a critical vulnerability in Splunk Enterprise that allows unauthenticated attackers to create or modify files via a PostgreSQL sidecar service endpoint. With confirmed exploitation and inclusion in CISA’s KEV catalog, the flaw poses a serious risk to system integrity and availability. Immediate patching or service mitigation is strongly recommended.
RedLegg will occasionally communicate vulnerabilities released outside the usual release schedule to provide additional value to our customers. These emergency bulletins describe vulnerabilities or threats we classify as the highest severity level and warrant out-of-band emergency patching or mitigation action.
VULNERABILITIES
Unauthenticated Arbitrary File Creation and Truncation in a PostgreSQL Sidecar Service Endpoint in Splunk Enterprise
Identifier: CVE-2026-20253
PoC or Exploitation:
CISA added CVE-2026-20253 to the Known Exploited Vulnerabilities (KEV) Catalog on June 12, 2026, confirming exploitation in the wild.
CVSS Score: 9.8 (Critical, CVSS v3.1)
Update / Patch:
Splunk has released security updates addressing CVE-2026-20253.
Affected Versions
- Splunk Enterprise 10.2.0 through 10.2.3
- Splunk Enterprise 10.0.0 through 10.0.6
Not Affected
- Splunk Enterprise 9.4 and earlier
Fixed Versions
- Splunk Enterprise 10.2.4 and later
- Splunk Enterprise 10.0.7 and later
- Splunk Enterprise 10.4.0 and later
Description:
CVE-2026-20253 is a critical vulnerability affecting Splunk Enterprise that allows unauthenticated arbitrary file creation and truncation through a PostgreSQL sidecar service endpoint.
An attacker who can reach the vulnerable service over the network may interact with the endpoint without providing valid credentials.
Successful exploitation allows an attacker to create arbitrary files or truncate existing files on the affected system.
Mitigation Recommendation:
Immediately upgrade affected Splunk Enterprise deployments to a fixed version.
Prioritize remediation of internet-facing and externally accessible Splunk Enterprise instances.
If immediate patching is not feasible, disable the PostgreSQL sidecar service in accordance with Splunk guidance and restart affected systems.
Review Splunk logs, operating system logs, and security monitoring systems for indicators of unauthorized file creation, file truncation, suspicious service activity, or signs of compromise.
Restrict network access to Splunk management and service interfaces to trusted hosts and administrative networks.
Conduct compromise assessments on vulnerable systems, especially those exposed to untrusted networks.
