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Nagios XiApplication · Nagios

CVE-2021-36363

CRITICAL · 9.8 CVSS v3.1 Published 2021-09-28
Fix available
A fix is available. Upgrade to 5.8.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
Nagios XI before 5.8.5 has Incorrect Permission Assignment for migrate.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 · moderate confidence

Nagios XI before version 5.8.5 has a file permission misconfiguration on migrate.php. The migrate.php script, which handles database migration tasks and likely requires elevated privileges, has overly permissive access controls. This allows unauthorized users to potentially execute the migration script, leading to privilege escalation, database manipulation, or remote code execution.

MitigationRestrict file permissions on migrate.php to only allow authorized system users and the web server process to access the file. Ideally, migrate.php should not be web-accessible or should require proper authentication and authorization checks before execution.

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
Nagios XiApplication
Affected:< 5.8.5

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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

  1. Identify installed Nagios XI version
    Run 'cat /usr/local/nagiosxi/html/api.php' or check the Nagios XI admin interface under 'Admin' > 'System' > 'System Status' to find the version number
    Affected if The version displayed is less than 5.8.5 (e.g., 5.8.4, 5.7.0, etc.)
  2. Locate migrate.php file
    Search for migrate.php in the Nagios XI web directory, typically found at '/usr/local/nagiosxi/html/includes/migrate.php' or run 'find /usr/local/nagiosxi -name migrate.php'
    Affected if The file exists in the Nagios XI installation directory
  3. Check file permissions on migrate.php
    Run 'ls -la /usr/local/nagiosxi/html/includes/migrate.php' (or the actual path found) to view owner, group, and permission bits
    Affected if Permissions allow world-readability (o+r, 644 or higher) or group-readability that includes unauthorized users (e.g., 664, 644, 755, 775)
  4. Test web accessibility of migrate.php
    Attempt to access 'http://<nagios-server>/nagiosxi/includes/migrate.php' via curl or browser request and observe if the script executes or returns content
    Affected if The script is accessible via HTTP/HTTPS and returns any output rather than a 403 Forbidden or 404 Not Found error

You are affected if Nagios XI version is below 5.8.5 AND migrate.php exists with overly permissive file permissions AND is web-accessible without proper authentication.

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 5.8.5 or later
Fixed in 5.8.5
Interim mitigation

Restrict file permissions on migrate.php to only allow authorized system users and the web server process to access the file. Ideally, migrate.php should not be web-accessible or should require proper authentication and authorization checks before execution.

Recommended fix High confidence

Nagios XI 5.8.5

  1. 1. Back up the current Nagios XI installation, including the database and configuration files.
  2. 2. Download Nagios XI version 5.8.5 or later from the official Nagios website.
  3. 3. Run the upgrade installer as the root user: ./upgrade_x i
  4. 4. Follow the on-screen prompts to complete the upgrade process.
  5. 5. After upgrade, verify the migrate.php file permissions are correct (should not be world-writable).
  6. 6. Restart Nagios services to ensure all components are running properly.
  7. 7. Test that the web interface is accessible and functioning normally.
Caveat Standard Nagios XI upgrade - ensure backups before proceeding; review release notes for any configuration changes

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

Fix this in Nagios Xi Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

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-2021-36363 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