CVE-2026-20256
Reported by cisco · Published June 10, 2026
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.
Risk Scores
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Splunk | Splunk Enterprise | 10.2, 10.0, 9.4 |
| Splunk | Splunk Cloud Platform | 10.3.2512, 10.2.2510, 10.1.2507 |
| Splunk | Splunk Cloud Platform | 9.3.2411, 10.3.2512, 10.2.2510 |
| Splunk | Splunk Enterprise | 10.2, 10.0, 9.4 |
Timeline
- Jun 10, 2026 CVE Published
- Jun 10, 2026 CVE Updated
- Jun 11, 2026 Coalition ESS Score
- Jun 12, 2026 Security Advisory