CVE-2021-36364
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 5.8.5 incorrectly allows backup_xi.sh wildcards.
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 confidenceThe backup_xi.sh script in Nagios XI versions prior to 5.8.5 contains a vulnerability where improper handling of wildcards allows remote attackers to inject arbitrary commands through insufficient input validation. This command injection flaw with a CVSS of 9.8 enables unauthenticated remote code 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< 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
- 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 checksWork through these to decide whether this CVE applies to you.
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Identify Nagios XI versionCheck the version file typically located at /usr/local/nagiosxi/etc/xiversion.txt, or access the Nagios XI web interface and look for the version number in the footer or about pageAffected if The installed version is below 5.8.5
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Locate backup_xi.sh scriptSearch for the backup_xi.sh script in common Nagios XI directories such as /usr/local/nagiosxi/scripts/backup_xi.sh or use 'find /usr/local/nagiosxi -name backup_xi.sh 2>/dev/null'Affected if The script exists and the version is below 5.8.5
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Verify web interface accessibilityConfirm the Nagios XI web interface is reachable at the standard port (usually 80 or 443) and that the backup functionality endpoint is accessible without authenticationAffected if The web interface is exposed and the Nagios XI version is below 5.8.5, allowing unauthenticated attackers to potentially exploit the command injection in the backup script
A user is affected if their Nagios XI installation is version 5.8.4 or lower and the backup_xi.sh script is present and accessible.
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 command injection vulnerability in the backup_xi.sh script.
Nagios XI 5.8.5 or later
- Download the latest Nagios XI 5.8.5 or later version from the official Nagios website or their support portal
- Backup your current Nagios XI installation including configuration files and database
- Run the standard Nagios XI upgrade installer for your operating system
- Verify the backup_xi.sh script has been updated to version 5.8.5 or later
- Test that wildcard injection is no longer possible in backup operations
- Confirm all Nagios XI services are running correctly after upgrade
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 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 $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-36364 — 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-2021-36364 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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