CVE-2025-20378
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 10.0.1, 9.4.5, 9.3.7, 9.2.9, and Splunk Cloud Platform versions below 10.0.2503.5, 9.3.2411.111, and 9.3.2408.121, an unauthenticated attacker could craft a malicious URL using the `return_to` parameter of the Splunk Web login endpoint. When an authenticated user visits the malicious URL, it could cause an unvalidated redirect to an external malicious site. To be successful, the attacker has to trick the victim into initiating a request from their browser. The unauthenticated attacker should not be able to exploit the vulnerability at will.
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 confidenceAn open redirect vulnerability exists in Splunk Web's login endpoint where the `return_to` parameter is not validated. An unauthenticated attacker can craft a malicious URL containing an external site in the `return_to` parameter; when an authenticated user is tricked into visiting this URL, they are redirected to the attacker's controlled site. Successful exploitation requires social engineering to trick the victim into clicking the link.
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>= 9.2.0, < 9.2.9>= 9.3.0, < 9.3.7>= 9.4.0, < 9.4.5= 10.0.0>= 9.3.2408, < 9.3.2408.121>= 9.3.2411, < 9.3.2411.111>= 10.0.2503, < 10.0.2503.5CVSS 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
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 versionRun the command: splunk version or check $SPLUNK_HOME/etc/splunk.version for the exact version numberAffected if The installed version falls within one of these ranges: >= 9.2.0 and < 9.2.9, >= 9.3.0 and < 9.3.7, >= 9.4.0 and < 9.4.5, or equals 10.0.0
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Verify Splunk Web is enabledCheck the web.conf configuration file at $SPLUNK_HOME/etc/system/default/web.conf or $SPLUNK_HOME/etc/system/local/web.conf for the setting enableSplunkWeb = 1Affected if Splunk Web is enabled and the version is in the affected ranges listed above
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Check access to login endpointAttempt to access the Splunk Web login page at https://<your-splunk-host>:8000/en-US/account/login or observe if port 8000 is listening with netstat -an | grep 8000Affected if The Splunk Web interface is accessible on port 8000 and the version is affected
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Inspect return_to parameter behaviorIf Splunk Web is accessible, examine the login form for the return_to hidden field or URL parameter. In a test environment, observe if a crafted URL with return_to=http://example.com redirects to the external domain after authenticationAffected if The return_to parameter accepts and acts on arbitrary external domains and the version is affected
Your environment is affected if Splunk Web is enabled and the installed Splunk Enterprise version is 9.2.0 through 9.2.8, 9.3.0 through 9.3.6, 9.4.0 through 9.4.4, or exactly 10.0.0.
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 · scoped9.2.99.3.79.3.2408.121
Upgrade Splunk Enterprise to versions 10.0.1, 9.4.5, 9.3.7, or 9.2.9 (or later); upgrade Splunk Cloud Platform to versions 10.0.2503.5, 9.3.2411.111, or 9.3.2408.121 (or later) to remediate this vulnerability.
Splunk Enterprise: 9.2.9, 9.3.7, 9.4.5, or 10.0.1 (depending on your current branch); Splunk Cloud Platform: 9.3.2408.121, 9.3.2411.111, or 10.0.2503.5
- 1. Identify your current Splunk Enterprise or Splunk Cloud Platform version using the Splunk web interface (Settings > Server settings > About Splunk) or CLI (`splunk --version`).
- 2. For Splunk Enterprise: Determine which upgrade path applies based on your current major version (9.2.x, 9.3.x, 9.4.x, or 10.0.0).
- 3. For Splunk Enterprise: Plan the upgrade to reach a fixed version: upgrade to 9.2.9 or later if on 9.2.x; upgrade to 9.3.7 or later if on 9.3.x; upgrade to 9.4.5 or later if on 9.4.x; upgrade to 10.0.1 or later if on 10.0.0.
- 4. For Splunk Cloud Platform: Contact Splunk Support or your Splunk Cloud administrator to request upgrade to the fixed cloud version matching your deployment (9.3.2408.121, 9.3.2411.111, or 10.0.2503.5).
- 5. Review Splunk Upgrade Planning documentation and release notes for your target version before upgrading.
- 6. Back up your Splunk environment including configurations and apps.
- 7. Test the upgrade in a non-production environment first.
- 8. Schedule a maintenance window and perform the upgrade during low-usage period.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-20378 — 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-2025-20378 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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- Version or environment caveats, and links to real fixes
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