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Nagios XiApplication · Nagios

CVE-2021-36365

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 repairmysql.sh.

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 confidence

Nagios XI versions before 5.8.5 contain the repairmysql.sh script with overly permissive file permissions, allowing unprivileged local users to potentially modify or execute this script with elevated privileges. This permission misconfiguration enables local privilege escalation.

MitigationUpdate Nagios XI to version 5.8.5 or later, which contains the corrected permission assignment for repairmysql.sh.

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 Nagios XI installation and version
    Run 'rpm -q nagios-xi' or check the version via the web interface under 'Admin > System Information'. Alternatively, look for /usr/local/nagiosxi/ and check version files.
    Affected if The installed version is before 5.8.5 (the version number is lower than 5.8.5)
  2. Locate the repairmysql.sh script
    Find the script by running 'find / -name repairmysql.sh 2>/dev/null' or check common paths like '/usr/local/nagiosxi/scripts/repairmysql.sh' and '/opt/nagiosxi/scripts/repairmysql.sh'.
    Affected if The script exists on the system (its presence is required for the vulnerability to apply)
  3. Check file permissions on repairmysql.sh
    Run 'ls -la /path/to/repairmysql.sh' (use the path found in step 2). Look for permissions that allow unprivileged users to modify the file, such as world-writable (o+w), group-writable (g+w), or weak owner/owner-group permissions.
    Affected if The file permissions allow write access to non-privileged users (e.g., permissions include 'w' for 'other' or group, or the file is not properly secured)
  4. Verify script ownership and SUID/SGID bits
    Run 'ls -la /path/to/repairmysql.sh' and check if the file is owned by root and has SUID (setuid) or SGID (setgid) bits set that could enable privilege escalation when executed.
    Affected if The script is owned by root and has elevated permissions (SUID/SGID) that could be exploited for privilege escalation

The system is affected if Nagios XI version is below 5.8.5 AND the repairmysql.sh script exists with permissions allowing unprivileged users to modify or execute it with elevated privileges.

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

Update Nagios XI to version 5.8.5 or later, which contains the corrected permission assignment for repairmysql.sh.

Recommended fix High confidence

Nagios XI 5.8.5 or later

  1. 1. Back up the current Nagios XI installation and database before proceeding with any upgrade.
  2. 2. Download Nagios XI 5.8.5 or later from the official Nagios website (www.nagios.com) or the assets.nagios.com download area.
  3. 3. Run the standard Nagios XI upgrade script: ./upgrade_xl or follow the web-based upgrade procedure.
  4. 4. After upgrade completes, verify the repairmysql.sh script permissions are correct (should not be world-writable or owned by a privileged user without proper restrictions).
  5. 5. Restart Nagios services to ensure changes take effect: systemctl restart nagios xi
Caveat Standard Nagios XI upgrade risks apply - test in non-production first, ensure backups are verified

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

Fix this in Nagios Xi Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.

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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-2021-36365 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