In Splunk Enterprise versions below 10.2.4, 10.0.7, 9.4.12, and 9.3.13, and Splunk Cloud Platform versions below 10.3.2512.13, 10.2.2510.15, 10.1.2507.23, and 9.3.2411.132, a low-privileged user that does not hold the ‘admin’ or ‘power’ Splunk roles could cause data exfiltration through classic dashboards by redirecting a victim to an external site using a protocol-relative URL in a drill-down link. The vulnerability exists because the URL classifier in classic dashboards only recognizes http:// and https:// schemes when checking for external URLs. Protocol-relative URLs such as //attacker.com bypass this check entirely, and Splunk Web does not show the external- warning dialog to the victim. See Classic Dashboards Trusted Domains List and role-based user access in the Splunk documentation.
Upgrade Splunk Enterprise to versions 10.4.0, 10.2.4, 10.0.7, 9.4.12, and 9.3.13, or higher. Splunk is actively monitoring and patching Splunk Cloud Platform instances.
Configure the Dashboards Trusted Domains List to restrict which external domains dashboards can load content from. See Classic Dashboards Trusted Domains List in the Splunk documentation. Review and restrict which roles have permission to create and edit classic dashboards. See role-based user access in the Splunk documentation.
Splunk rates this vulnerability a 5.7, Medium, with a CVSSv3.1 vector of CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N.
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