Splunk has issued critical security updates to address CVE-2026-20253, a severe vulnerability in Splunk Enterprise that allows unauthenticated users to perform arbitrary file operations and potentially achieve remote code execution. Rated 9.8 on the CVSS scoring system, the flaw presents a significant risk to enterprise environments utilizing the affected software. The company announced the fix this week, urging immediate patching to mitigate exploitation.
The vulnerability stems from a lack of authentication controls in a PostgreSQL sidecar service endpoint within Splunk Enterprise. This oversight enables any user on the network to interact with the service without providing credentials, leading to unauthorized access and manipulation of files. Splunk Cloud, however, is not affected by this particular issue.
Understanding the Splunk Enterprise Vulnerability
WatchTowr Labs recently provided in-depth technical details surrounding CVE-2026-20253, elaborating on how threat actors could leverage it for pre-authenticated remote code execution. The exploit chain focuses on two specific endpoints: “/v1/postgres/recovery/backup” and “/v1/postgres/recovery/restore.” These endpoints, when targeted, can be manipulated to compromise the integrity of Splunk Enterprise systems.
The attack unfolds in a multi-step process. Initially, an attacker can connect to a compromised database and use the “/backup” endpoint to dump its contents into an arbitrary file on the vulnerable Splunk system. This acquired data can then be used to overwrite the local PostgreSQL instance’s data. The crucial step involves including a “passfile” argument during the restore operation, pointing to a “.pgpass” file that contains credentials for the “postgres_admin” user. This allows the attacker to control the SQL queries that are subsequently executed by Splunk’s PostgreSQL instance.
Security researchers Piotr Bazydlo and Yordan Ganchev explained that through this process, attackers gain the ability to authenticate and restore attacker-controlled SQL commands. By weaponizing this capability, they can define new functions, such as one utilizing `lo_export`, to write arbitrary content to files on the Splunk file system. This file write primitive is a stepping stone to more damaging actions.
Achieving Remote Code Execution
With the ability to freely write to the Splunk file system, threat actors can elevate their privileges to achieve remote code execution. This is typically accomplished by overwriting critical Python scripts that Splunk regularly executes. For example, a script like “/opt/splunk/etc/apps/splunk_secure_gateway/bin/ssg_enable_modular_input.py” could be modified to include malicious code. When Splunk runs this compromised script, the attacker’s payload is executed, granting them full control over the system.
The complete attack sequence involves creating a database that permits unauthenticated user authentication and grants sufficient privileges for functions like `lo_export`. The attacker then uses the “/backup” endpoint to transfer a dump of this remote database to the Splunk file system. Subsequently, the “/restore” endpoint is used to load the malicious dump, triggering the execution of the attacker-controlled function and writing a malicious Python script to the Splunk file system, ultimately leading to remote code execution.
While there is currently no public evidence of CVE-2026-20253 being actively exploited in the wild, the detailed disclosure of the vulnerability and its exploit mechanics significantly increases the risk of opportunistic attacks. Organizations using affected versions of Splunk Enterprise are strongly advised to apply the security updates provided by Splunk without delay. The affected versions are Splunk Enterprise versions 10.0.0 through 10.0.6 (fixed in 10.0.7) and 10.2.0 through 10.2.3 (fixed in 10.2.4). Splunk Enterprise 10.4 is not affected. Continued vigilance and prompt patching remain the most effective defense against such critical cybersecurity threats.