Splunk patches critical flaw allowing low-privileged users to achieve RCE

Splunk has announced that it has addressed several security vulnerabilities identified in third-party packages used in Splunk Enterprise, Splunk Cloud Platform and the MCP Server application.

According to the disclosed information, the high-severity vulnerability tracked as  CVE-2026-20204, affecting Splunk Enterprise and Splunk Cloud Platform, could be exploited by low-privileged users. It has been reported that, through this flaw, an attacker could upload a malicious file to a temporary directory and achieve remote code execution (RCE).

According to the company, the vulnerability exists due to the improper handling of temporary files and insufficient isolation within that directory. As a result, a low-privileged user who does not hold the admin or power Splunk roles could potentially perform remote code execution by uploading a malicious file to the $SPLUNK_HOME/var/run/splunk/apptemp directory.

In addition, two medium-severity vulnerabilities in Splunk Enterprise and Splunk Cloud Platform have also been addressed. One of these flaws could be exploited to create usernames containing a null byte or a non-UTF-8 percent-encoded byte, preventing their conversion into a proper format. The other vulnerability allowed attackers to turn the “Data Model Acceleration” feature on or off.

Users are advised to upgrade to Splunk Enterprise versions 10.2.2, 10.0.5, 9.4.10, 9.3.11, or later, which contain fixes for all of these security defects. For Splunk Cloud Platform environments, the company states that the necessary updates are being applied directly by Splunk.

The company has also announced that it has resolved the high-severity vulnerability tracked as CVE-2026-20205 in the MCP Server application. According to the information provided, this flaw could allow an authenticated attacker to view users’ sessions and authorization tokens in clear text. However, successful exploitation would require either local access to the log files or administrative access to internal indexes. Splunk notes that, by default, only the administrator role is granted such privileges. Fixes for the vulnerability were included in MCP Server app version 1.0.3.