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SplunkApplication

CVE-2025-20387

MEDIUM · 6.5 CVSS v3.1 Published 2025-12-03
Fix available
A fix is available. Upgrade to 9.2.10 / 9.3.8 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

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 · unedited
In Splunk Universal Forwarder for Windows versions below 10.0.2, 9.4.6, 9.3.8, and 9.2.10, a new installation of or an upgrade to an affected version can result in incorrect permissions assignment in the Universal Forwarder for Windows Installation directory. This lets non-administrator users on the machine access the directory and all its contents.

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 confidence

In Splunk Universal Forwarder for Windows versions below 10.0.2, 9.4.6, 9.3.8, and 9.2.10, a new installation or upgrade results in overly permissive access controls on the installation directory, allowing non-administrator users read and potentially write access to sensitive forwarder binaries and configuration files.

MitigationUpgrade Splunk Universal Forwarder for Windows to version 10.0.2 or later, or the appropriate patched version (9.4.6, 9.3.8, or 9.2.10) per the version branch in use.

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
SplunkApplication
Affected:>= 9.2.0, < 9.2.10>= 9.3.0, < 9.3.8>= 9.4.0, < 9.4.6>= 10.0.0, < 10.0.2

CVSS 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
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Splunk Universal Forwarder for Windows is installed
    Look for the Splunk Universal Forwarder service in Windows Services, or check for the Splunk installation directory (commonly C:\Program Files\SplunkUniversalForwarder or C:\SplunkUniversalForwarder)
    Affected if Splunk Universal Forwarder for Windows is not present on the system
  2. Identify the installed version
    Locate the version file in the installation directory (typically named 'VERSION' or accessible via 'splunk --version' command from the bin directory)
    Affected if Unable to determine the version or the version is below 9.2.10, 9.3.8, 9.4.6, or 10.0.2
  3. Compare version against affected ranges
    Check if the installed version falls within: >= 9.2.0 and < 9.2.10, OR >= 9.3.0 and < 9.3.8, OR >= 9.4.0 and < 9.4.6, OR >= 10.0.0 and < 10.0.2
    Affected if The installed version matches any of the affected ranges listed
  4. Examine directory permissions for excessive access
    Use icacls or the Security tab in the installation directory properties to inspect which users and groups have access. Look for permissions granted to Users or non-administrator accounts
    Affected if Non-administrator users (such as Users group) are granted Read and Write permissions to the installation directory

If Splunk Universal Forwarder for Windows is installed with a version in the affected ranges AND the installation directory grants non-administrator users read or write access, the environment is affected by this CVE.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 9.2.10 / 9.3.8 / 9.4.6 or later
Fixed in 9.2.109.3.89.4.6
Interim mitigation

Upgrade Splunk Universal Forwarder for Windows to version 10.0.2 or later, or the appropriate patched version (9.4.6, 9.3.8, or 9.2.10) per the version branch in use.

Recommended fix High confidence

Upgrade to Splunk Universal Forwarder for Windows version 9.2.10, 9.3.8, 9.4.6, or 10.0.2 (matching your current major version)

  1. 1. Identify the current version of Splunk Universal Forwarder for Windows by checking Add/Remove Programs or running: splunk --version
  2. 2. Determine which upgrade path applies based on your current major version (9.2.x -> 9.2.10, 9.3.x -> 9.3.8, 9.4.x -> 9.4.6, 10.0.x -> 10.0.2)
  3. 3. Back up your Splunk Universal Forwarder configuration and any custom inputs.conf, outputs.conf, or other configuration files
  4. 4. Download the appropriate fixed version from https://www.splunk.com/en_us/download/universal-forwarder.html
  5. 5. Install or upgrade to the fixed version following Splunk's standard upgrade documentation
  6. 6. After installation, verify that the installation directory permissions are correct: only administrators and the SYSTEM account should have full control; standard users should have read/execute only or no access
  7. 7. Confirm non-administrator users can no longer write to or modify files in the Splunk installation directory
Caveat Review Splunk upgrade documentation for your version; standard forwarder upgrades are generally non-disruptive but test in non-production first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Splunk Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-20387 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data