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Debian LinuxOperating system · Debian

CVE-2019-13486

CRITICAL · 9.8 CVSS v3.0 Published 2019-08-27
Fix available
A fix is available. Upgrade to after 4.3.28 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
In Xymon through 4.3.28, a stack-based buffer overflow exists in the status-log viewer component because of   expansion in svcstatus.c.

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

A stack-based buffer overflow vulnerability exists in the status-log viewer component of Xymon (through version 4.3.28) in svcstatus.c. The vulnerability is triggered by the expansion of the HTML entity ' ' (non-breaking space), which exceeds the allocated buffer size on the stack, leading to potential memory corruption and possible remote code execution.

MitigationUpgrade to a patched version of Xymon beyond 4.3.28, or implement input validation/size checking around the   expansion logic in svcstatus.c to ensure the expanded output fits within the allocated buffer.

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
Debian LinuxOperating system
Affected:= 8.0
XymonApplication
Affected:<= 4.3.28

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. Identify if Xymon is installed
    Check for Xymon installation using package manager commands (dpkg -l | grep xymon, rpm -qa | grep xymon) or locate the xymon binary via 'which xymon' or 'find / -name xymon -type f 2>/dev/null'
    Affected if Xymon is not found on the system, then the CVE does not apply
  2. Determine installed Xymon version
    Run 'xymon --version' or check the package version via dpkg/rpm query, or examine the svcstatus.c file if accessible to identify the version string
    Affected if The installed version is 4.3.28 or lower, or the version cannot be determined but Xymon is present
  3. Verify status-log viewer component is accessible
    Check if the Xymon web interface is configured and accessible by accessing the /svcstatus URL path on the Xymon server (typically port 80 or 8080)
    Affected if The status-log viewer web component is accessible and operational
  4. Confirm vulnerable code path exists
    Locate and examine the svcstatus.c source file in the Xymon installation (typically in /home/xymon/source or /usr/src/xymon) and search for the '&nbsp;' expansion logic
    Affected if The svcstatus.c file contains the '&nbsp;' HTML entity expansion code without proper bounds checking

A system is affected if Xymon is installed with version 4.3.28 or lower AND the status-log viewer component (svcstatus.c) with the vulnerable &nbsp; expansion logic is present and accessible.

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 a release after 4.3.28
Interim mitigation

Upgrade to a patched version of Xymon beyond 4.3.28, or implement input validation/size checking around the &nbsp; expansion logic in svcstatus.c to ensure the expanded output fits within the allocated buffer.

Recommended fix Moderate confidence

Xymon version greater than 4.3.28 (e.g., 4.3.29 or latest stable release)

  1. 1. Identify the current Xymon version installed by checking the package manager or xymon --version
  2. 2. For Debian systems, check for available security updates via 'apt-get update' and 'apt-cache policy xymon'
  3. 3. If a newer fixed version is available in Debian security repositories, apply via 'apt-get install xymon' or 'apt-get upgrade'
  4. 4. Alternatively, obtain the latest Xymon source from the official Xymon project and rebuild
  5. 5. After upgrade, restart Xymon services to apply the patched version
  6. 6. Verify the fix by confirming the new version is running: 'xymon --version'
Caveat Minor: Verify custom configurations remain compatible with the new version after upgrade

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2019-13486 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