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NagiosApplication

CVE-2016-0726

CRITICAL · 9.8 CVSS v3.0 Published 2017-06-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
The Fedora Nagios package uses "nagiosadmin" as the default password for the "nagiosadmin" administrator account, which makes it easier for remote attackers to obtain access by leveraging knowledge of the credentials.

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

The Fedora Nagios package ships with a hardcoded, static default credential (username: nagiosadmin, password: nagiosadmin) for the administrative web interface. Attackers with network access to the Nagios service can trivially authenticate as administrators using these well-known default credentials, gaining full control over the monitoring system and potentially the underlying host.

MitigationImmediately change the default 'nagiosadmin' password to a strong, unique credential and restrict network access to the Nagios web interface using firewall rules or VPN to prevent unauthorized external access.

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
NagiosApplication
Affected:all versions

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:3.0/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. Verify Nagios web interface is accessible
    Check if the Nagios web interface is running by accessing the URL (typically http://localhost/nagios or http://localhost:80/nagios) and confirming the login prompt appears
    Affected if The web interface responds with a login prompt, indicating Nagios is running and accessible
  2. Attempt authentication with default credentials
    Try logging into the Nagios web interface using username 'nagiosadmin' and password 'nagiosadmin'. This can be done via web browser or programmatically with curl: curl -u nagiosadmin:nagiosadmin http://TARGET/nagios/
    Affected if Login succeeds with these credentials, confirming the default password is still active
  3. Check htpasswd authentication file
    Locate the Nagios htpasswd file (commonly at /etc/nagios/passwd or /etc/httpd/conf/htpasswd.users) and examine its contents. If using Apache, check /etc/httpd/conf.d/nagios.conf for the auth file path. View the file with: cat /path/to/htpasswd.file
    Affected if The file contains an entry for 'nagiosadmin' with a password hash that corresponds to 'nagiosadmin' (or the file is the default shipped with the package)
  4. Determine if network access is exposed
    Check if the Nagios web server is listening on external interfaces (0.0.0.0) rather than localhost only. Run: netstat -tlnp | grep -E 'nagios|httpd' or ss -tlnp | grep -E 'nagios|httpd'. Also check firewall rules: iptables -L -n | grep -E '80|443'
    Affected if Nagios listens on non-localhost addresses (0.0.0.0) and firewall permits external access on ports 80/443

You are affected if the Nagios web interface responds to login attempts and accepts the default credentials nagiosadmin:nagiosadmin, especially if it is network-accessible beyond localhost.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Immediately change the default 'nagiosadmin' password to a strong, unique credential and restrict network access to the Nagios web interface using firewall rules or VPN to prevent unauthorized external access.

Recommended fix Moderate confidence
  1. During or after Nagios installation, immediately change the default 'nagiosadmin' password to a strong, unique password using the web interface (Configuration > Users > nagiosadmin > Modify) or via the command line with htpasswd /etc/nagios/passwd nagiosadmin
  2. Ensure the new password meets organizational complexity requirements and is not shared across multiple systems
  3. If Nagios was deployed with the default Fedora package credentials, verify that the password has been changed before exposing the system to network access
  4. For additional security, consider disabling the default 'nagiosadmin' account and creating a new administrator account with appropriate privileges

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

Fix this in Nagios Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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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-2016-0726 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
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  • Version or environment caveats, and links to real fixes
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