dbcve.org
UltravncApplication · Uvnc

CVE-2018-15361

CRITICAL · 9.8 CVSS v3.0 Published 2019-03-05
Fix available
A fix is available. Upgrade to 1.2.2.3 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 buffer underflow vulnerability in VNC client code, which can potentially result in 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 buffer underflow vulnerability in its VNC client code that is exploitable remotely via network connectivity and could potentially allow code execution. The vulnerability was addressed in revision 1199.

MitigationUpgrade UltraVNC to revision 1199 or later to remediate the buffer underflow vulnerability.

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

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. Verify UltraVNC installation
    Check for UltraVNC in the list of installed programs (Add/Remove Programs on Windows) or look for the uvnc.exe executable in common installation paths such as C:\Program Files\UltraVNC or C:\Program Files (x86)\UltraVNC
    Affected if UltraVNC is found installed on the system
  2. Identify installed version number
    Right-click on the vncviewer.exe or winvnc.exe file in the UltraVNC installation directory, select Properties, and check the File Version tab. Alternatively, launch UltraVNC Viewer and navigate to Help > About to view the version and revision number
    Affected if The displayed version is below 1.2.2.3 or the revision number shown is 1198 or earlier
  3. Confirm affected client component
    Verify that the VNC client (vncviewer.exe) is the component in use. This vulnerability exists in the VNC client code, so check if the system runs vncviewer.exe or connects to remote VNC servers
    Affected if The VNC client component is present and active on the system, and the version falls below 1.2.2.3
  4. Check running processes
    Open Task Manager or use command line tools (tasklist /v) to list running processes and look for vncviewer.exe or winvnc.exe
    Affected if A vncviewer.exe process is running and its version is below 1.2.2.3

The environment is affected if UltraVNC is installed with a version lower than 1.2.2.3 (or revision 1198), particularly when the VNC client component is in use.

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 or later
Fixed in 1.2.2.3
Interim mitigation

Upgrade UltraVNC to revision 1199 or later to remediate the buffer underflow vulnerability.

Recommended fix High confidence

UltraVNC 1.2.2.3 or later (revision 1199+)

  1. 1. Identify all systems running UltraVNC versions prior to 1.2.2.3
  2. 2. Download the latest stable UltraVNC version 1.2.2.3 or later from the official UltraVNC website or a trusted distribution point
  3. 3. Close any running UltraVNC instances (both viewer and server components)
  4. 4. Install the updated UltraVNC version on all affected client and server systems
  5. 5. Verify the installed version by checking Help > About in the UltraVNC viewer or server
  6. 6. Restart any VNC services that were running

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
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

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Scan for this in your stack

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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-2018-15361 in production — separate from our analysis above.

No notes yet

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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