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UltravncApplication · Uvnc

CVE-2019-8258

CRITICAL · 9.8 CVSS v3.1 Published 2019-03-05
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 1198 has a heap buffer overflow vulnerability in VNC client code which results code execution. This attack appears to be exploitable via network connectivity. This vulnerability has been fixed in revision 1199.

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 1198 contains a heap buffer overflow vulnerability in the VNC client code. The overflow occurs during client-side processing and can be triggered remotely via network connectivity, allowing remote code execution by an attacker.

MitigationUpgrade UltraVNC to revision 1199 or later to obtain the patched version. If upgrading is not immediately possible, restrict network access to VNC services and disable unused VNC client functionality.

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 installed UltraVNC version
    Check the installed UltraVNC version through the program's About dialog, or use the version information displayed when launching the UltraVNC Viewer (vncviewer.exe). Compare the version number to the affected range of < 1.2.2.3.
    Affected if The installed UltraVNC version is lower than 1.2.2.3
  2. Check for Siemens Sinumerik products with bundled VNC
    Identify if the system has Siemens Sinumerik software installed (such as Access Mymachine/p2p, Pcu Base Win10 Software/ipc, or Pcu Base Win7 Software/ipc). These products bundle UltraVNC components.
    Affected if A Siemens Sinumerik product is installed with a version below 4.8 (for Access Mymachine/p2p), below 14.00 (for Pcu Base Win10), or at or below 12.01 (for Pcu Base Win7)
  3. Verify VNC client functionality is in use
    Determine whether the UltraVNC Viewer (client component) is actively used or configured on the system. Check for scheduled tasks, startup entries, or user-initiated connections that invoke the VNC client to connect to remote VNC servers.
    Affected if The VNC client component is enabled and capable of initiating outbound connections to remote VNC servers
  4. Assess network exposure of VNC services
    Review firewall rules and network configuration to determine if the system is accessible on VNC default ports (typically 5900+). Use netstat or similar tools to identify listening VNC-related ports and evaluate whether the VNC client can communicate with untrusted remote hosts.
    Affected if The system can make outbound VNC connections to untrusted or internet-facing VNC servers

You are affected if UltraVNC version is below 1.2.2.3 (or a vulnerable Siemens Sinumerik version is present) AND the VNC client functionality is enabled and can reach potentially malicious VNC servers over the network.

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 1199 or later to obtain the patched version. If upgrading is not immediately possible, restrict network access to VNC services and disable unused VNC client functionality.

Recommended fix High confidence

UltraVNC 1.2.2.3 (or later stable release) / revision 1199; Siemens: Sinumerik Access Mymachine/p2p >= 4.8, Sinumerik Pcu Base Win10 >= 14.00, Sinumerik Pcu Base Win7 >= 14.00

  1. 1. Identify the current UltraVNC version installed by checking Help > About in the UltraVNC viewer or server
  2. 2. Download the fixed UltraVNC version 1.2.2.3 or later from the official UltraVNC website or a trusted distribution source
  3. 3. Uninstall the current vulnerable version of UltraVNC from all affected systems
  4. 4. Install the patched version 1.2.2.3 (or latest stable release) on all previously affected machines
  5. 5. Verify the installation by checking Help > About confirms the version is 1.2.2.3 or higher
  6. 6. For Siemens Sinumerik products (Access Mymachine/p2p, Pcu Base Win7/Win10), apply vendor-specific patches: upgrade to version 4.8 or later for Access Mymachine/p2p, 14.00 or later for Win10 IPC, and version 14.00 (newer than 12.01) for Win7 IPC

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

Fix this in Ultravnc Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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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-2019-8258 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