CVE-2019-8268
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 · uneditedUltraVNC revision 1206 has multiple off-by-one vulnerabilities in VNC client code connected with improper usage of ClientConnection::ReadString function, which can potentially result code execution. This attack appears to be exploitable via network connectivity. These vulnerabilities have been fixed in revision 1207.
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 confidenceMultiple off-by-one vulnerabilities in UltraVNC revision 1206's VNC client code due to improper usage of the ClientConnection::ReadString function, which can lead to buffer overflows and potential remote code execution when the client connects to a malicious 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< 1.2.2.3< 4.8< 14.00<= 12.01CVSS 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:3.1/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 checksWork through these to decide whether this CVE applies to you.
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Identify if UltraVNC client is installedCheck for UltraVNC installation by looking in Program Files for 'UltraVNC' folder, or check Windows registry at HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall for UltraVNC entry, or search for uvnc.exe in system directoriesAffected if UltraVNC client software is found on the system
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Determine UltraVNC versionRight-click on uvnc.exe (typically in C:\Program Files\UltraVNC or C:\Program Files (x86)\UltraVNC), select Properties, then view the Details tab for version information; alternatively, open UltraVNC and check Help > AboutAffected if The version is lower than 1.2.2.3 (such as revision 1206) or the version cannot be determined
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Identify Siemens Sinumerik software installationsCheck Windows registry at HKLM\SOFTWARE\Siemens for Sinumerik entries, or look in Program Files for folders starting with 'Sinumerik', or check Control Panel > Programs and Features for Siemens Sinumerik applicationsAffected if Siemens Sinumerik software is installed on the system
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Check Siemens Sinumerik version against affected rangesFor Sinumerik Access Mymachine/p2p: check version in Add/Remove Programs or the application's About section - affected if version < 4.8. For Sinumerik Pcu Base Win10 Software/ipc: affected if version < 14.00. For Sinumerik Pcu Base Win7 Software/ipc: affected if version <= 12.01Affected if Any Siemens Sinumerik software matches the affected version ranges specified
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Assess client usage exposureDetermine if the UltraVNC client is configured to connect to remote VNC servers; check UltraVNC settings or VNC connection files (.vnc files) for server addresses; note that exploitation requires the client to connect to a malicious VNC serverAffected if The system has UltraVNC client installed (version < 1.2.2.3) and is used or configured to connect to remote VNC servers
A user is affected if UltraVNC client version lower than 1.2.2.3 (including revision 1206) or any Siemens Sinumerik software with versions matching the affected ranges is installed and the client is used to connect to VNC servers.
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 · scoped1.2.2.34.814.00
Upgrade UltraVNC from revision 1206 to revision 1207 to apply the security patch that fixes the off-by-one vulnerabilities in the ReadString function.
UltraVNC revision 1207 (or version 1.2.2.3 and later); Sinumerik products to versions >= 4.8, >= 14.00, or > 12.01 respectively
- 1. Identify the specific UltraVNC or Sinumerik product and current version installed in your environment
- 2. For UltraVNC: Download and install UltraVNC revision 1207 or later from the official UltraVNC repository
- 3. For Sinumerik Access Mymachine/p2p: Upgrade to version 4.8 or later
- 4. For Sinumerik Pcu Base Win10 Software/ipc: Upgrade to version 14.00 or later
- 5. For Sinumerik Pcu Base Win7 Software/ipc: Upgrade to a version greater than 12.01
- 6. After upgrade, verify the installed version matches the fixed release
- 7. Test VNC client functionality to ensure the upgrade does not break legitimate operations
- 8. Review any related configuration changes required by the new version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-8268 — 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-2019-8268 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
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