CVE-2021-37348
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 · uneditedNagios XI before version 5.8.5 is vulnerable to local file inclusion through improper limitation of a pathname in index.php.
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 confidenceNagios XI before version 5.8.5 contains a local file inclusion (LFI) vulnerability in index.php caused by improper path limitation. Attackers can exploit this to read arbitrary files on the server by manipulating path parameters, potentially exposing sensitive system files, configuration data, and credentials.
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< 5.8.5CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Nagios XI versionRun the command: cat /usr/local/nagiosxi/html/api.php?cmd=getversion or check the Nagios XI admin interface under 'About' or 'System Diagnostics'. Alternatively, check the version file if present in the installation directory.Affected if The installed version is earlier than 5.8.5 (e.g., 5.8.0, 5.7.0, 5.6.0, etc.)
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Verify index.php is accessibleConfirm the Nagios XI web interface is running and index.php exists in the document root (typically /usr/local/nagiosxi/html/ or /var/www/html/nagiosxi/). Check if the web server is actively serving the application.Affected if index.php is present and the web interface is accessible without additional authentication barriers blocking the path traversal vector
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Check for path traversal vulnerability in index.phpReview the index.php source code for vulnerable path handling parameters. Look for code that processes 'dir', 'path', 'file', or similar parameters without proper sanitization. Search for patterns like 'include($_GET[...])' or 'readfile($_GET[...])' handling user-supplied path input.Affected if index.php contains code that accepts path parameters from user input and passes them to file inclusion functions without validation or path traversal prevention
A user is affected if their Nagios XI installation is version 5.8.4 or earlier and the web interface with index.php is accessible, allowing path traversal attacks to read arbitrary files.
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 · scoped5.8.5
Upgrade Nagios XI to version 5.8.5 or later to remediate this vulnerability. If immediate upgrade is not feasible, implement web application firewall (WAF) rules to block path traversal patterns in HTTP requests.
Nagios XI 5.8.5 or later
- 1. Back up the current Nagios XI installation and database before upgrading
- 2. Download Nagios XI version 5.8.5 or later from the official Nagios website (www.nagios.com)
- 3. Run the Nagios XI upgrade installer following the official upgrade documentation
- 4. Verify the upgrade was successful and the version is 5.8.5 or later
- 5. Test that the web interface functions normally after the upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-37348 — 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-2021-37348 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
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