CVE-2021-26253: 
Splunk Forwarder vulnerability analysis and mitigation

CVE-2021-26253 is a vulnerability discovered in Splunk Enterprise's implementation of DUO Multi-Factor Authentication (MFA). The vulnerability affects Splunk Enterprise versions prior to 8.1.6 and allows attackers to bypass MFA verification. It specifically impacts Splunk Enterprise instances configured to use DUO MFA but does not affect any DUO product or service directly (Vendor Advisory).

The vulnerability has been assigned a CVSSv3.1 Base Score of 8.1 (High severity) with the vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. This indicates that the vulnerability is network-accessible, requires high attack complexity, needs no privileges or user interaction, has unchanged scope, and could result in high impacts to confidentiality, integrity, and availability. The vulnerability is classified under CWE-287 (Improper Authentication) (Vendor Advisory).

If successfully exploited, the vulnerability could lead to complete bypass of MFA verification in affected Splunk Enterprise instances. This could potentially result in unauthorized access with high impacts on system confidentiality, integrity, and availability (Vendor Advisory).

The recommended mitigation is to upgrade affected Splunk Enterprise instances using DUO MFA to version 8.1.6 or later. The vulnerability does not impact Splunk Cloud Platform instances (Vendor Advisory).