CVE-2019-15680
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 · uneditedTightVNC code version 1.3.10 contains null pointer dereference in HandleZlibBPP function, which results Denial of System (DoS). This attack appear to be exploitable via network connectivity.
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 confidenceTightVNC 1.3.10 has a null pointer dereference vulnerability in the HandleZlibBPP function that causes a denial of service when exploited via network connectivity. An attacker can send specially crafted packets to trigger the null dereference, crashing the VNC server.
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= 1.3.10CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Confirm TightVNC is installedCheck for TightVNC installation: On Windows, look in Program Files for TightVNC folder, or check registry key HKLM\SOFTWARE\TightVNC. On Linux, check /usr/bin/vncserver or run 'which vncserver'. On any OS, check if port 5900 (default VNC) is listening with 'netstat -an | grep 5900' or 'ss -tlnp | grep 5900'.Affected if TightVNC is installed and running as a server listening on network ports
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Verify the installed version is 1.3.10On Windows, check the version property of tvnserver.exe in the TightVNC installation folder, or run 'tvnserver.exe -version' if supported. On Linux, check the package version with 'rpm -q tightvnc' or 'dpkg -l tightvnc'. Compare the result to the affected version 1.3.10.Affected if The installed TightVNC version is exactly 1.3.10
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Confirm VNC server is network-accessibleCheck if the TightVNC service is running and bound to a network interface. Run 'netstat -an | grep 5900' or 'ss -tlnp | grep 5900' to see if VNC is listening on TCP port 5900 (or 5901+ for display :1, etc.). Verify the listening address is not 127.0.0.1 only.Affected if The VNC server is bound to a non-localhost interface and accepts remote connections
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Check if Zlib compression is enabledTightVNC supports multiple encoding types. The vulnerability exists in HandleZlibBPP, which handles Zlib-compressed pixel data. Check the TightVNC server configuration for encoding preferences, typically in tvnserver.conf or through the TightVNC server settings UI under 'Encoding' or 'Compression' options.Affected if Zlib encoding is permitted or set as a preferred encoding option in the TightVNC configuration
You are affected if TightVNC version 1.3.10 is installed, the VNC server is running and accessible over the network, and Zlib encoding is enabled in the server configuration.
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.
From vendor dataApply vendor patches for TightVNC 1.3.10 or upgrade to a patched version. If no patch is available, implement network-level access controls to limit VNC exposure to trusted hosts only.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-15680 — 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-2019-15680 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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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.
- 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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