What’s Vulnerable › Vulnerabilities
CVE-2026-20256: Improper Input Validation through Protocol-Relative URL in Classic Dashboards in Splunk Enterprise
- Severity: medium (CVSS 5.7 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-06-10 · updated 2026-06-17
- Weakness: CWE-20
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
- Splunk Enterprise: from 9.3.0 before 9.3.13; from 9.4.0 before 9.4.12; from 10.0.0 before 10.0.7; from 10.2.0 before 10.2.4 — fixed in 10.0.7, 10.2.4, 9.3.13, 9.4.12
- Splunk Cloud Platform: from 9.3.2411 before 9.3.2411.132; from 10.1.2507 before 10.1.2507.23; from 10.2.2510 before 10.2.2510.15; from 10.3.2512 before 10.3.2512.13 — fixed in 10.1.2507.23, 10.2.2510.15, 10.3.2512.13, 9.3.2411.132
How to fix
Upgrade to a fixed version: Splunk Enterprise 10.0.7, 10.2.4, 9.3.13, 9.4.12; Splunk Cloud Platform 10.1.2507.23, 10.2.2510.15, 10.3.2512.13, 9.3.2411.132. Check the vendor advisory for mitigations.
References
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