CVE-2026-20256
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA URL validation bypass in Splunk Enterprise and Cloud Platform's classic dashboards allows low-privileged users to craft drill-down links using protocol-relative URLs (e.g., //attacker.com) that bypass the external URL classifier. Since the classifier only checks for http:// and https:// schemes, the external-navigation warning dialog is suppressed, enabling data exfiltration to external domains.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 9.3.0, < 9.3.13>= 9.4.0, < 9.4.12>= 10.0.0, < 10.0.7>= 10.2.0, < 10.2.4>= 9.3.2411, < 9.3.2411.132>= 10.1.2507, < 10.1.2507.23>= 10.2.2510, < 10.2.2510.15>= 10.3.2512, < 10.3.2512.13CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check Splunk Enterprise versionNavigate to About > About Splunk in the web UI, or run: splunk --version or cat $SPLUNK_HOME/etc/splunk.versionAffected if Version is >= 9.3.0 and < 9.3.13, OR >= 9.4.0 and < 9.4.12, OR >= 10.0.0 and < 10.0.7, OR >= 10.2.0 and < 10.2.4
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Check Splunk Cloud Platform versionNavigate to Settings > About in the Splunk Cloud web UI, or use the cloud management API endpoint for version infoAffected if Version is >= 9.3.2411 and < 9.3.2411.132, OR >= 10.1.2507 and < 10.1.2507.23, OR >= 10.2.2510 and < 10.2.2510.15, OR >= 10.3.2512 and < 10.3.2512.13
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Determine if classic dashboards are in useLook for .xml based dashboards in $SPLUNK_HOME/etc/apps/ or search for 'dashboard.conf' with 'dashboard.legacy' settings. Check savedsearches.conf for Simple XML dashboards.Affected if Classic (legacy) dashboards are actively used and accessible to low-privileged users
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Check user role permissions for drill-down link configurationReview roles in Settings > Users and Roles. Check if user roles with 'user' or 'power' level have write access to savedsearches.conf, views, or dashboard XML files.Affected if Low-privileged users (user role) have ability to create or modify drill-down links in classic dashboards
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Verify external URL classifier behaviorCreate a test drill-down link using protocol-relative URL format (//example.com) and observe if the external-navigation warning dialog appears.Affected if No external URL warning dialog appears when using protocol-relative URLs in drill-down links
User is affected if Splunk version is within any of the affected ranges AND classic dashboards are enabled AND low-privileged users can configure drill-down links without seeing an external URL warning for protocol-relative URLs.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped9.3.139.3.2411.1329.4.12
Upgrade to Splunk Enterprise 10.2.4, 10.0.7, 9.4.12, or 9.3.13 (or later) and Splunk Cloud Platform 10.3.2512.13, 10.2.2510.15, 10.1.2507.23, or 9.3.2411.132 (or later). Alternatively, disable classic dashboards or restrict drill-down link configuration to admin/power roles.
Splunk Enterprise: 10.2.4, 10.0.7, 9.4.12, or 9.3.13 (depending on current major version); Splunk Cloud Platform: 10.3.2512.13, 10.2.2510.15, 10.1.2507.23, or 9.3.2411.132
- Identify whether the deployment is Splunk Enterprise or Splunk Cloud Platform
- For Splunk Enterprise: Determine current version using the Splunk Web UI (Settings > Server settings > Server information) or by running: splunk --version
- For Splunk Enterprise versions 10.2.x: Upgrade to version 10.2.4 or later
- For Splunk Enterprise versions 10.0.x: Upgrade to version 10.0.7 or later
- For Splunk Enterprise versions 9.4.x: Upgrade to version 9.4.12 or later
- For Splunk Enterprise versions 9.3.x: Upgrade to version 9.3.13 or later
- For Splunk Cloud Platform: Contact Splunk Support to request upgrade to the fixed version (9.3.2411.132, 10.1.2507.23, 10.2.2510.15, or 10.3.2512.13)
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-20256 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-20256 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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