Splunk CVE-2026-20253: CVSS 9.8 RCE Exploited in the Wild

The cybersecurity landscape faces a critical threat today. CISA confirmed active exploitation of Splunk CVE-2026-20253. Consequently, administrators must patch this CVSS 9.8 flaw immediately. This severe vulnerability affects Splunk Enterprise deployments. Specifically, it targets the PostgreSQL sidecar service endpoint. Therefore, hackers can achieve pre-authenticated remote code execution. Furthermore, CISA added this flaw to its Known Exploited Vulnerabilities catalog.

Understanding the Authentication Bypass

The core issue involves missing authentication controls. Specifically, the PostgreSQL sidecar service lacks proper security checks. Therefore, any network-reachable user can invoke file operations without credentials. This dangerous Splunk CVE-2026-20253 flaw allows attackers to create or truncate arbitrary files easily. Additionally, Towr Labs recently released technical details explaining the exploit. Hackers target the backup and restore endpoints specifically.

The Remote Code Execution Attack Chain

The attack sequence begins with a malicious database connection. First, the attacker dumps contents into an arbitrary file using the backup endpoint. Next, they load this dump into the local PostgreSQL instance. During this critical restore process, they use a passfile argument. This action exposes the administrative password effortlessly. Subsequently, the attacker’s SQL queries execute directly on the system. They weaponize the lo_export function to write malicious content to the file system. Finally, they overwrite a frequently executed Python script to gain full remote code execution.

Mitigation and Remediation Steps

Organizations must act swiftly to prevent devastating network breaches. Splunk Enterprise 10.2 versions below 10.2.4 remain highly vulnerable to attacks. Likewise, versions 10 below 10.0.7 need immediate patching to ensure safety. However, older deployments running versions 9.4 and earlier are completely safe. Sometimes, administrators cannot apply patches right away due to operational constraints. If you cannot upgrade immediately, a reliable temporary workaround exists. You can simply disable the PostgreSQL sidecar service entirely. This action effectively blocks the attack vector. Furthermore, Federal Civilian Executive Branch agencies face a strict compliance deadline. They must remediate this critical Splunk CVE-2026-20253 flaw by June 21, 2026. Ultimately, applying the official software updates remains the only permanent security solution.

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Written by

@DdoS · Security Researcher

Do Son

Do Son is the Founder and Editor of SecurityOnline.info. Working in cybersecurity since 2013, he reports on vulnerabilities, malware, and emerging threats, providing timely analysis to help organizations and individuals stay ahead of evolving risks.