Vulnerability · Published Jun 10, 2026 · Assigned by cisco
CVE-2026-20256Improper Input Validation through Protocol-Relative URL in Classic Dashboards in Splunk Enterprise
Medium 5.7
In plain English
A medium-severity improper input validation in Splunk Cloud Platform from Splunk. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Splunk | Splunk Enterprise | 10.2 – before 10.2.410.0 – before 10.0.79.4 – before 9.4.129.3 – before 9.3.13 |
| Splunk | Splunk Cloud Platform | 10.3.2512 – before 10.3.2512.1310.2.2510 – before 10.2.2510.1510.1.2507 – before 10.1.2507.239.3.2411 – before 9.3.2411.132 |
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N