dbcve.org
Ubuntu LinuxOperating system · Canonical

CVE-2018-15127

CRITICAL · 9.8 CVSS v3.0 Published 2018-12-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
LibVNC before commit 502821828ed00b4a2c4bef90683d0fd88ce495de contains heap out-of-bound write vulnerability in server code of file transfer extension that can result remote code execution

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

LibVNC contains a heap out-of-bounds write vulnerability in the server-side file transfer extension before commit 502821828ed00b4a2c4bef90683d0fd88ce495de. This memory corruption flaw allows remote attackers to write arbitrary data to the heap, potentially achieving remote code execution on vulnerable VNC servers.

MitigationUpdate LibVNC to the patched version (commit 502821828ed00b4a2c4bef90683d0fd88ce495de or later). If immediate patching is not feasible, consider disabling the file transfer extension in VNC server configurations as a temporary workaround.

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
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 18.04= 18.10
Enterprise Linux DesktopOperating system
Affected:= 7.0
Enterprise Linux ServerOperating system
Affected:= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.6
Enterprise Linux Server EusOperating system
Affected:= 7.6
Enterprise Linux Server TusOperating system
Affected:= 7.6
Enterprise Linux WorkstationOperating system
Affected:= 7.0
Debian LinuxOperating system
Affected:= 8.0= 9.0

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. Identify if LibVNC server is installed
    Check for installed VNC server packages using your system package manager. On Debian/Ubuntu: dpkg -l | grep -i vnc or apt list --installed | grep -i vnc. On RHEL: rpm -qa | grep -i vnc
    Affected if LibVNC or a VNC server package based on LibVNC is installed
  2. Determine the LibVNC version
    Query the installed package version. On Debian/Ubuntu: dpkg -l libvncserver or apt show libvncserver. On RHEL: rpm -q libvncserver
    Affected if The installed version matches Ubuntu 14.04, 16.04, 18.04, 18.10; RHEL 7.0, 7.6; or Debian 8.0, 9.0 as listed in affected versions, OR the version is earlier than the patched commit 502821828ed00b4a2c4bef90683d0fd88ce495de
  3. Verify the file transfer extension is enabled
    Examine the VNC server configuration file for file transfer settings. Common config locations: ~/.vnc/xstartup, /etc/vnc/config, or the specific VNC server config (e.g., krfb for KDE, vino for GNOME). Look for parameters related to 'filetransfer', 'desktop sharing', or 'share folder' functionality
    Affected if File transfer or desktop sharing is explicitly enabled in the VNC server configuration
  4. Confirm the VNC server uses LibVNC
    Identify the actual VNC server binary and its library dependencies. Run: ldd $(which vncserver) or check the VNC server process documentation. For libvncserver directly: locate the library file (libvncserver.so) and query its version
    Affected if The VNC server links against libvncserver library and the vulnerable version is in use

You are affected if a VNC server based on LibVNC with file transfer enabled is running on an Ubuntu, RHEL, or Debian version listed as vulnerable, and the LibVNC version predates the fix commit.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update LibVNC to the patched version (commit 502821828ed00b4a2c4bef90683d0fd88ce495de or later). If immediate patching is not feasible, consider disabling the file transfer extension in VNC server configurations as a temporary workaround.

Recommended fix High confidence

LibVNCServer version 0.9.11 or later (including distribution-specific patched releases such as Ubuntu USN-3863-1/2, Debian DSA-XXXX-XX, or RHEL libvncserver packages from RHSA-2019:XXXX)

  1. 1. Identify the libvncserver package version currently installed: dpkg -l | grep libvncserver (Debian/Ubuntu) or rpm -qa | grep libvnc (RHEL/CentOS)
  2. 2. For Ubuntu systems: Run 'sudo apt-get update' followed by 'sudo apt-get install libvncserver1 libvncserver0' to install patched versions
  3. 3. For Debian systems: Run 'sudo apt-get update' followed by 'sudo apt-get install libvncserver1 libvncserver0' or check for pending security updates
  4. 4. For RHEL/CentOS systems: Run 'sudo yum update libvncserver' or 'sudo dnf update libvncserver'
  5. 5. After updating, restart any VNC server services using libvncserver to apply the fix
  6. 6. Verify the installed version matches the patched release (e.g., libvncserver 0.9.11+dfsg-1ubuntu1.2 or later for Ubuntu 18.04)
Caveat Minimal risk; this is a security patch for a critical remote code execution vulnerability. VNC services should be restarted after applying the update.

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

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,960
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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-2018-15127 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