HOMEVULNERABILITIESCVE-2018-20748
CRITICAL

CVE-2018-20748

CWE-787Published: January 30, 2019· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

LibVNC before 0.9.12 contains multiple heap out-of-bounds write vulnerabilities in libvncclient/rfbproto.c. The fix for CVE-2018-20019 was incomplete.

NVD Source

Technical Analysis

CVE-2018-20748 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-787): Out-of-bounds write vulnerabilities can lead to data corruption, crashes, or arbitrary code execution.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

Canonical1 product(s)
ubuntu linux
Debian1 product(s)
debian linux
libvnc_project1 product(s)
libvncserver
siemens12 product(s)
simatic itc1500 firmwaresimatic itc1500simatic itc1500 pro firmwaresimatic itc1500 prosimatic itc1900 firmwaresimatic itc1900simatic itc1900 pro firmwaresimatic itc1900 prosimatic itc2200 firmwaresimatic itc2200simatic itc2200 pro firmwaresimatic itc2200 pro
Source: NVD CPE · 18 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdf
PATCHhttps://github.com/LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42bae
PATCHhttps://github.com/LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7
PATCHhttps://github.com/LibVNC/libvncserver/commit/c5ba3fee85a7ecbbca1df5ffd46d32b92757bc2a
PATCHhttps://github.com/LibVNC/libvncserver/commit/e34bcbb759ca5bef85809967a268fdf214c1ad2c
PATCHhttps://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdf
PATCHhttps://github.com/LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42bae
PATCHhttps://github.com/LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7
PATCHhttps://github.com/LibVNC/libvncserver/commit/c5ba3fee85a7ecbbca1df5ffd46d32b92757bc2a
PATCHhttps://github.com/LibVNC/libvncserver/commit/e34bcbb759ca5bef85809967a268fdf214c1ad2c
ADVISORYhttps://github.com/LibVNC/libvncserver/issues/273
ADVISORYhttps://lists.debian.org/debian-lts-announce/2019/01/msg00029.html
ADVISORYhttps://lists.debian.org/debian-lts-announce/2019/10/msg00042.html
ADVISORYhttps://usn.ubuntu.com/3877-1/
ADVISORYhttps://usn.ubuntu.com/4547-1/
ADVISORYhttps://usn.ubuntu.com/4587-1/
ADVISORYhttps://www.openwall.com/lists/oss-security/2018/12/10/8
ADVISORYhttps://github.com/LibVNC/libvncserver/issues/273
ADVISORYhttps://lists.debian.org/debian-lts-announce/2019/01/msg00029.html
ADVISORYhttps://lists.debian.org/debian-lts-announce/2019/10/msg00042.html
ADVISORYhttps://usn.ubuntu.com/3877-1/
ADVISORYhttps://usn.ubuntu.com/4547-1/
ADVISORYhttps://usn.ubuntu.com/4587-1/
ADVISORYhttps://www.openwall.com/lists/oss-security/2018/12/10/8

All References (24)

→
https://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdfPatch · Third Party Advisory
→
https://github.com/LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42baePatch · Third Party Advisory
→
https://github.com/LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7Patch · Third Party Advisory
→
https://github.com/LibVNC/libvncserver/commit/c5ba3fee85a7ecbbca1df5ffd46d32b92757bc2aPatch · Third Party Advisory
→
https://github.com/LibVNC/libvncserver/commit/e34bcbb759ca5bef85809967a268fdf214c1ad2cPatch · Third Party Advisory
→
https://github.com/LibVNC/libvncserver/issues/273Issue Tracking · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2019/01/msg00029.htmlMailing List · Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2019/10/msg00042.htmlMailing List · Third Party Advisory
→
https://usn.ubuntu.com/3877-1/Third Party Advisory
→
https://usn.ubuntu.com/4547-1/Third Party Advisory
→
https://usn.ubuntu.com/4587-1/Third Party Advisory
→
https://www.openwall.com/lists/oss-security/2018/12/10/8Exploit · Mailing List · Third Party Advisory
→
https://cert-portal.siemens.com/productcert/pdf/ssa-390195.pdfPatch · Third Party Advisory
→
https://github.com/LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42baePatch · Third Party Advisory
→
https://github.com/LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7Patch · Third Party Advisory

Quick Facts

CVE IDCVE-2018-20748
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-787
CISA KEVNo
Affected4 vendor(s)
PublishedJan 30, 2019

Related CVEs (CWE-787)

CVE-2013-5610
10.0
CVE-2012-3957
10.0
CVE-2012-0751
10.0
CVE-2011-1807
10.0
CVE-2004-0978
10.0
CVE-2014-1478
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2018-20748 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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