Splunk Enterprise: Pre-Authentication RCE via PostgreSQL Sidecar CVE-2026-20253
CVE-2026-20253 is a critical vulnerability in Splunk Enterprise stemming from an unauthenticated PostgreSQL sidecar service endpoint. Attackers can issue unauthenticated HTTP requests to the sidecar port to perform arbitrary file creation and modification operations. By leveraging these file write primitives, an unauthenticated remote attacker can overwrite critical configuration files or inject malicious binaries, escalating the flaw to Remote Code Execution (RCE). With a CVSS score of 9.8, this vulnerability bypasses application-level authentication entirely. Given its active exploitation in the wild and inclusion in the CISA Known Exploited Vulnerabilities (KEV) catalog, immediate patching and forensic investigation of Splunk installation directories are required to mitigate the risk of full system compromise.