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UltravncApplication · Uvnc

CVE-2019-8271

CRITICAL · 9.8 CVSS v3.1 Published 2019-03-08
Fix available
A fix is available. Upgrade to 1.2.2.3 / 4.8 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
UltraVNC revision 1211 has a heap buffer overflow vulnerability in VNC server code inside file transfer handler, which can potentially result code execution. This attack appears to be exploitable via network connectivity. This vulnerability has been fixed in revision 1212.

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

UltraVNC revision 1211 contains a heap buffer overflow vulnerability in the VNC server's file transfer handler. The overflow occurs when processing file transfer requests, allowing an attacker to overwrite heap memory and potentially execute arbitrary code via network connectivity.

MitigationUpgrade UltraVNC to revision 1212 or later to patch the heap buffer overflow in the file transfer handler. Restrict network access to VNC servers and monitor for unusual file transfer activity as interim hardening measures.

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
UltravncApplication
Affected:< 1.2.2.3
Sinumerik Access Mymachine\/p2pApplication
Affected:< 4.8
Sinumerik Pcu Base Win10 Software\/ipcApplication
Affected:< 14.00
Sinumerik Pcu Base Win7 Software\/ipcApplication
Affected:<= 12.01

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:3.1/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify UltraVNC installation and version
    Check the UltraVNC version by inspecting the file properties of uvnc_service.exe or winvnc.exe in the UltraVNC installation directory, typically found in C:\Program Files\UltraVNC or C:\Program Files (x86)\UltraVNC. Right-click the executable, select Properties, and view the Version tab.
    Affected if The version number displayed is less than 1.2.2.3 (for example, 1.2.2.0, 1.2.1.x, or earlier)
  2. Check Siemens Sinumerik product version
    For Siemens Sinumerik systems, identify the installed version through the Windows Programs and Features list or the specific software's About/Info dialog. Record the full version number.
    Affected if The product is Siemens Sinumerik Access Mymachine/p2p with version < 4.8, Siemens Sinumerik Pcu Base Win10 Software/ipc with version < 14.00, or Siemens Sinumerik Pcu Base Win7 Software/ipc with version <= 12.01
  3. Verify file transfer is enabled
    Open UltraVNC's settings (UltraVNC Settings > Admin Properties or the system tray menu) and examine whether the File Transfer enabled option is checked. On systems with UltraVNC Service, check the uvnc_settings.txt or registry keys under HKLM\Software\ORL\WinVNC3 for the FileTransferEnabled parameter.
    Affected if File Transfer is enabled in the UltraVNC configuration (the vulnerability resides in the file transfer handler component)

You are affected if UltraVNC version is below 1.2.2.3 (or the corresponding Siemens Sinumerik version is below the safe thresholds listed) AND file transfer is enabled in the VNC server settings.

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 1.2.2.3 / 4.8 / 14.00 or later
Fixed in 1.2.2.34.814.00
Interim mitigation

Upgrade UltraVNC to revision 1212 or later to patch the heap buffer overflow in the file transfer handler. Restrict network access to VNC servers and monitor for unusual file transfer activity as interim hardening measures.

Recommended fix High confidence

UltraVNC 1.2.2.3 (revision 1212) or later; Sinumerik Access Mymachine/p2p >= 4.8; Sinumerik Pcu Base Win10 Software/ipc >= 14.00; Sinumerik Pcu Base Win7 Software/ipc >= 12.02

  1. 1. Identify the exact UltraVNC or Sinumerik product and version currently installed in the environment
  2. 2. For UltraVNC: Download UltraVNC revision 1212 or version 1.2.2.3 (or later) from the official UltraVNC repository or vendor website
  3. 3. For Sinumerik Access Mymachine/p2p: Upgrade to version 4.8 or later
  4. 4. For Sinumerik Pcu Base Win10 Software/ipc: Upgrade to version 14.00 or later
  5. 5. For Sinumerik Pcu Base Win7 Software/ipc: Upgrade to version 12.02 or later
  6. 6. Test the upgrade in a non-production environment to ensure compatibility
  7. 7. Deploy the upgrade to production systems, preferably during a planned maintenance window
  8. 8. Verify the VNC server is running the fixed version and file transfer functionality works correctly

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

Fix this in Ultravnc Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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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-2019-8271 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