CVE-2018-20903
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 · uneditedcPanel before 71.9980.37 allows self XSS in the WHM Backup Configuration interface (SEC-421).
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 confidencecPanel before version 71.9980.37 contains a self Cross-Site Scripting (XSS) vulnerability in the WHM (Web Host Manager) Backup Configuration interface. An attacker could inject malicious JavaScript code through input fields in the backup configuration, which would execute in the context of the authenticated user's browser when they view the affected page.
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< 71.9980.37CVSS 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:3.0/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 the installed cPanel versionLog into WHM and navigate to Server Status > cPanel Version, or run the command: /usr/local/cpanel/cpanel -VAffected if The installed version is lower than 71.9980.37 (e.g., 70.x, 71.x below 71.9980.37)
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Verify WHM access is enabledConfirm the server runs cPanel/WHM by checking if port 2087 is open and responding, or check for /usr/local/cpanel in the filesystemAffected if WHM is installed and accessible on this server
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Confirm Backup Configuration feature existsLog into WHM and navigate to Backup > Backup Configuration, or check for backup configuration files in /var/cpanel/backups/Affected if The Backup Configuration interface is present and configurable on this system
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Check for unauthenticated or low-privilege access vectorsReview WHM user account configurations to determine which roles can access the Backup Configuration interfaceAffected if Multiple users or resellers have access to WHM Backup Configuration
You are affected if your cPanel installation version is below 71.9980.37 AND the WHM Backup Configuration interface is accessible to users on your server.
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.
From vendor data71.9980.37
Update cPanel to version 71.9980.37 or later. This is a straightforward software update that remediates the self XSS vulnerability in the WHM Backup Configuration interface.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 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 $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-20903 — 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-2018-20903 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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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.
- 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