CVE-2021-37223
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 Enterprises NagiosXI <= 5.8.4 contains a Server-Side Request Forgery (SSRF) vulnerability in schedulereport.php. Any authenticated user can create scheduled reports containing PDF screenshots of any view in the NagiosXI application. Due to lack of input sanitisation, the target page can be replaced with an SSRF payload to access internal resources or disclose local system files.
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 confidenceNagiosXI versions 5.8.4 and below contain an SSRF vulnerability in schedulereport.php where authenticated users can manipulate the screenshot target parameter to make the server request arbitrary URLs. The lack of input sanitization on the report target allows attackers to access internal resources or exfiltrate local system files through the PDF report generation feature.
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<= 5.8.4CVSS 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
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
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 installed NagiosXI versionCheck the version by viewing /usr/local/nagiosxi/var/version.txt or accessing the Nagios XI admin interface footer which displays the version number.Affected if Installed version is 5.8.4 or lower.
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Verify schedulereport.php existsLocate the schedulereport.php file in the NagiosXI web root, typically found in /usr/local/nagiosxi/html/includes/components/nagioscore/ or similar paths under the web document root.Affected if The file exists and is accessible via the web server.
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Confirm authenticated access is possibleCheck if user authentication is enabled and valid user accounts exist in the NagiosXI database (mysql -u nagiosxi -p -D nagiosxi -e 'SELECT username FROM nagiosql_users;' or similar query).Affected if Any valid user credentials can be obtained or created, enabling the authenticated SSRF attack path.
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Inspect HTTP access logs for suspicious requestsReview web server access logs (Apache error/access logs or Nginx access logs) for GET/POST requests to schedulereport.php containing unusual target parameters, especially requests to internal IP addresses (127.0.0.1, 10.x.x.x, 192.168.x.x) or non-standard ports.Affected if Log entries show requests to schedulereport.php with target parameters pointing to internal resources, localhost, or unexpected external URLs.
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Check for outbound SSRF indicatorsExamine system network connections and firewall logs for unexpected outbound connections originating from the NagiosXI server to internal resources or unusual external hosts, particularly around the time of report generation requests.Affected if The server initiated outbound connections to internal network ranges or unexpected external hosts that were not part of normal NagiosXI operations.
A user is affected if NagiosXI version is 5.8.4 or below AND schedulereport.php is accessible to at least one authenticated user, with potential compromise indicated by suspicious requests in web logs targeting internal resources.
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 · scopedUpgrade NagiosXI to a version newer than 5.8.4 that includes proper input sanitization, or implement strict URL allowlisting and input validation on schedulereport.php parameters to restrict report targets to legitimate internal NagiosXI views only.
Nagios XI 5.8.5 or later (latest stable release)
- Upgrade Nagios XI to version 5.8.5 or later
- After upgrade, verify the schedulereport.php component no longer accepts arbitrary URLs
- Test that scheduled reports function normally with internal Nagios XI views only
- Review audit logs for any suspicious scheduled report creations that may have occurred prior to patching
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing5.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-37223 — 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-2021-37223 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
- No spam, self-promotion, credentials, or personal data