Splunk Enterprise and Cloud Platform
CVE-2026-20256: Improper Input Validation through Protocol-Relative URL in Classic Dashboards in Splunk Enterprise
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.<br><br>The vulnerability exists because the URL classifier in classic dashboards only recognizes `http://` and `https://` schemes when checking for external URLs.
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Splunk Enterprise 10.2 | 10.2.4 or later |
| Splunk Enterprise 10.0 | 10.0.7 or later |
| Splunk Enterprise 9.4 | 9.4.12 or later |
| Splunk Enterprise 9.3 | 9.3.13 or later |
| Splunk Cloud Platform 10.3 | 10.3.2512.13 or later |
| Splunk Cloud Platform 10.2 | 10.2.2510.15 or later |
| Splunk Cloud Platform 10.1 | 10.1.2507.23 or later |
| Splunk Cloud Platform 9.3 | 9.3.2411.132 or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
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.<br><br>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-navigation warning dialog to the victim.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 13 Oct 2026.