Splunk Enterprise - Authentication Bypass (CVE-2026-20253)

CVE-2026-20253 is a critical authentication bypass vulnerability in Splunk Enterprise and Splunk Cloud Platform, where unauthenticated users can create or truncate arbitrary files via a PostgreSQL sidecar service endpoint. This flaw arises from missing authentication controls, enabling remote attackers to perform unauthorized file operations, which could lead to data loss, system compromise, or further exploitation of the affected environment.

CrowdSec has been tracking this vulnerability and its exploits since 15th of June 2026.

According to CrowdSec data, while opportunistic exploitation dominates, a portion of threat actors trying to exploit CVE-2026-20253 apply basic targeting methods such as port or service detection. This indicates emerging patterns of selective targeting. Additionally, according to week-over-week analysis by CrowdSec, exploitation of CVE-2026-20253 is surging. Attack volumes are spiking well above historical norms, indicating widespread and escalating interest from threat actors. CVE-2026-20253 is currently experiencing high visibility and active exploitation across the internet.

Attackers exploit the Splunk PostgreSQL Sidecar Service by sending POST requests to endpoints matching /splunkd/__raw/v1/postgres/recovery/backup, often with a Basic Authorization header, to attempt unauthorized access or trigger error-based detection artifacts.