CVE-2026-20202
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 10.2.2, 10.0.5, 9.4.10, and 9.3.11, and Splunk Cloud Platform versions below 10.4.2603.0, 10.3.2512.6, 10.2.2510.10, 10.1.2507.20, 10.0.2503.13, and 9.3.2411.127, a user who holds a role that contains the high-privilege capability `edit_user`could create a specially crafted username that includes a null byte or a non-UTF-8 percent-encoded byte due to improper input validation.<br><br>This could lead to inconsistent conversion of usernames into a proper format for storage and account management inconsistencies, such as being unable to edit or delete affected users.
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 confidenceIn Splunk Enterprise and Cloud Platform versions listed, improper input validation allows users with edit_user capability to create usernames containing null bytes or non-UTF-8 percent-encoded bytes. This causes inconsistent username conversion during storage, leading to account management issues where affected users cannot be edited or deleted.
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, < 9.3.11>= 9.4.0, < 9.4.10>= 10.0.0, < 10.0.5>= 10.2.0, < 10.2.2>= 9.3.2411, < 9.3.2411.127>= 10.0.2503, < 10.0.2503.13>= 10.1.2507, < 10.1.2507.20>= 10.2.2510, < 10.2.2510.10>= 10.3.2512, < 10.3.2512.6CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:H/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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Check Splunk Enterprise versionRun: splunk --version or check etc/splunk-buildinfo in $SPLUNK_HOMEAffected if Installed version falls within any of these ranges: 9.3.0-9.3.10, 9.4.0-9.4.9, 10.0.0-10.0.4, or 10.2.0-10.2.1
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Check Splunk Cloud Platform versionNavigate to Settings > About > About Splunk in the web UI, or check via splunkcloud.com tenantAffected if Installed version falls within any of these ranges: 9.3.2411-9.3.2411.126, 10.0.2503-10.0.2503.12, 10.1.2507-10.1.2507.19, 10.2.2510-10.2.2510.9, or 10.3.2512-10.3.2512.5
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Verify if edit_user capability existsNavigate to Settings > Users and Authentication > Users, or query the authentication/users endpoint via REST APIAffected if Any non-admin users have the edit_user capability assigned (these users could potentially create malformed usernames)
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Inspect user list for malformed usernamesExport user list via REST: /services/authentication/users?output_mode=json. Look for usernames containing %00 (null byte) or percent-encoded sequences like %XX that are non-UTF-8Affected if Any usernames in the system contain null bytes or non-UTF-8 percent-encoded characters
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Test user editabilityAttempt to edit or delete a user account via Settings > Users or REST API POST to /services/authentication/users/{username}/_acl or DELETE methodAffected if Any user account cannot be edited or deleted and returns an error related to username parsing or user not found
User is affected if running a vulnerable Splunk version AND there are users with null-byte or non-UTF-8 encoded usernames in the system that cannot be edited or deleted.
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 · scoped9.3.119.3.2411.1279.4.10
Upgrade Splunk Enterprise to version 10.2.2, 10.0.5, 9.4.10, or 9.3.11 (or higher), or upgrade Splunk Cloud Platform to the patched versions specified by Splunk.
Splunk Enterprise: 9.3.11, 9.4.10, 10.0.5, or 10.2.2 (or later); Splunk Cloud Platform: 9.3.2411.127, 10.0.2503.13, 10.1.2507.20, or 10.2.2510.10 (or cloud-managed equivalent)
- 1. Identify the current Splunk Enterprise or Splunk Cloud Platform version by navigating to Settings > About > About Splunk in the web interface, or running 'splunk version' from CLI
- 2. For Splunk Enterprise: If running 9.3.x, upgrade to 9.3.11 or later; if running 9.4.x, upgrade to 9.4.10 or later; if running 10.0.x, upgrade to 10.0.5 or later; if running 10.2.x, upgrade to 10.2.2 or later
- 3. For Splunk Cloud Platform: Contact Splunk Support to request the appropriate patch version (9.3.2411.127, 10.0.2503.13, 10.1.2507.20, or 10.2.2510.10)
- 4. Review Splunk Upgrade Guidelines at docs.splunk.edu for pre-upgrade checklist including app compatibility and backup procedures
- 5. Perform a full backup of Splunk configuration ($SPLUNK_HOME/var and $SPLUNK_HOME/etc directories)
- 6. Schedule a maintenance window as username-related operations will be affected during upgrade
- 7. Execute the upgrade following Splunk's standard upgrade procedure
- 8. After upgrade, verify that user management functions work correctly by attempting to edit and delete test users
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 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-2026-20202 — 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-2026-20202 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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