CVE-2021-26253
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 · uneditedA potential vulnerability in Splunk Enterprise's implementation of DUO MFA allows for bypassing the MFA verification in Splunk Enterprise versions before 8.1.6. The potential vulnerability impacts Splunk Enterprise instances configured to use DUO MFA and does not impact or affect a DUO product or service.
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 · moderate confidenceA vulnerability in Splunk Enterprise's DUO MFA integration allows attackers to bypass the multi-factor authentication verification, potentially gaining unauthorized access to Splunk instances. The flaw exists in how Splunk processes DUO MFA challenges before version 8.1.6.
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>= 8.1.0, < 8.1.6CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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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Identify Splunk Enterprise installationRun 'splunk --version' or check the $SPLUNK_HOME/etc/splunk.version file to determine the installed Splunk versionAffected if The installed version is 8.1.0 through 8.1.5 (versions >= 8.1.0 and < 8.1.6)
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Locate Splunk configuration directoryCheck the default installation path (typically /opt/splunk or C:\Program Files\Splunk) and navigate to $SPLUNK_HOME/etc/system/default/Affected if The Splunk installation directory exists and contains configuration files
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Verify DUO MFA is configuredExamine the authentication.conf file in $SPLUNK_HOME/etc/system/local/ or $SPLUNK_HOME/etc/system/default/ for 'DUO' or 'mfa' settings under the [authentication] stanzaAffected if DUO MFA is explicitly configured as the authentication method
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Confirm version is in vulnerable rangeCompare the identified Splunk version against the affected range: versions 8.1.0, 8.1.1, 8.1.2, 8.1.3, 8.1.4, or 8.1.5Affected if The version is 8.1.0 or higher but lower than 8.1.6 AND DUO MFA is enabled
You are affected if Splunk Enterprise version is 8.1.0 through 8.1.5 AND DUO MFA integration is configured and enabled in your environment.
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 · scoped8.1.6
Upgrade Splunk Enterprise to version 8.1.6 or later to remediate this MFA bypass vulnerability.
Splunk Enterprise 8.1.6 or later
- Check current Splunk Enterprise version (must be >= 8.1.0 and < 8.1.6)
- Confirm DUO MFA is configured on the Splunk Enterprise instance
- Schedule maintenance window for upgrade
- Upgrade Splunk Enterprise to version 8.1.6 or later
- After upgrade, test DUO MFA login flow to verify the vulnerability is remediated
- Review Splunk upgrade documentation for any additional prerequisites or post-upgrade steps
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-26253 — 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-2021-26253 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
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data