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Nagios XiApplication · Nagios

CVE-2021-33177

HIGH · 8.8 CVSS v3.1 Published 2021-10-14
Fix available
A fix is available. Upgrade to 5.8.5 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
The Bulk Modifications functionality in Nagios XI versions prior to 5.8.5 is vulnerable to SQL injection. Exploitation requires the malicious actor to be authenticated to the vulnerable system, but once authenticated they would be able to execute arbitrary sql queries.

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 prior to 5.8.5 contain a SQL injection vulnerability in the Bulk Modifications feature. An authenticated attacker can exploit this to execute arbitrary SQL queries against the database, potentially leading to data exfiltration, privilege escalation, or complete system compromise.

MitigationUpgrade Nagios XI to version 5.8.5 or later to patch the SQL injection vulnerability in the Bulk Modifications functionality.

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

CVSS:3.1/AV:N/AC:L/PR:L/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
    Check the file /usr/local/nagiosxi/html/config.inc.php for the version string, or run: cat /usr/local/nagiosxi/etc/xi-version.txt
    Affected if The version number found is less than 5.8.5 (e.g., 5.8.0, 5.7.0, etc.)
  2. Confirm the Bulk Modifications module exists
    Navigate to the Nagios XI web interface, then go to 'Bulk Tools' or 'Bulk Modifications' under the 'Configure' section. Alternatively, check if the directory /usr/local/nagiosxi/html/includes/components/bulkmod exists.
    Affected if The Bulk Modifications feature is present and accessible to authenticated users
  3. Verify authentication is enabled
    Check if the web interface requires login by accessing the Nagios XI URL. The vulnerability requires an authenticated session.
    Affected if Anonymous or low-privileged user accounts can access the Bulk Modifications feature
  4. Check for unauthorized database access
    Review the Nagios XI database for unexpected entries in tables such as nagiosql_* tables, or check MySQL/MariaDB logs for suspicious SQL queries from the web application user.
    Affected if Unusual or malicious SQL queries appear in database logs, or unexpected data exists in administrative tables
  5. Audit user accounts and privileges
    Query the nagiosxi database: SELECT * FROM nagiosxi_users; or check for new administrative accounts created after the software was installed.
    Affected if Unexpected user accounts exist, especially those with admin privileges not created by legitimate administrators

A user is affected if they are running any Nagios XI version prior to 5.8.5 with the Bulk Modifications feature accessible to authenticated users.

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

Upgrade Nagios XI to version 5.8.5 or later to patch the SQL injection vulnerability in the Bulk Modifications functionality.

Recommended fix High confidence

Nagios XI 5.8.5 or later

  1. 1. Back up the current Nagios XI installation, including the database and configuration files.
  2. 2. Verify system requirements for Nagios XI 5.8.5 are met.
  3. 3. Run the official Nagios XI update script: /usr/local/nagiosxi/xi-scripts/upgrade_to_latest.sh
  4. 4. Alternatively, download Nagios XI 5.8.5 from the official Nagios website and follow the installation guide.
  5. 5. After upgrade, verify the Bulk Modifications functionality works correctly.
  6. 6. Confirm the version number matches 5.8.5 or later using the Nagios XI admin interface or command: cat /usr/local/nagiosxi/etc/xi-version.txt
Caveat Review Nagios XI release notes for any configuration or feature changes between your current version and 5.8.5; test in staging before production deployment

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

Fix this in Nagios Xi Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,648.

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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-2021-33177 in production — separate from our analysis above.

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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