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No exploitation reportedFix available

CVE-2018-20748

No exploitation reported by the sources we read.

  • Published2019-01-30
  • WeaknessCWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2019-01-3018:29CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2018-20748?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2018-20748?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Canonical ubuntu linux
BranchAffectedFixed in
14.4= 14.04no fix published
16.4= 16.04no fix published
18.4= 18.04no fix published
18.10= 18.10no fix published
Debian debian linux
BranchAffectedFixed in
8.0= 8.0no fix published
Libvnc project libvncserver
BranchAffectedFixed in
0.9< 0.9.120.9.12

6 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • italcUbuntu:18.04:LTSall versions · fixed in 1:3.0.3+dfsg1-3ubuntu0.1
  • italcUbuntu:16.04:LTSall versions · fixed in 1:2.0.2+dfsg1-4ubuntu0.1
  • italcMageia:7all versions · fixed in 3.0.3-3.1.mga7
  • italcDebian:8all versions · fixed in 1:2.0.2+dfsg1-2+deb8u1
  • libvncserverUbuntu:18.04:LTSall versions · fixed in 0.9.11+dfsg-1ubuntu1.1
  • libvncserverUbuntu:16.04:LTSall versions · fixed in 0.9.10+dfsg-3ubuntu0.16.04.3
  • libvncserverUbuntu:14.04:LTSall versions · fixed in 0.9.9+dfsg-1ubuntu1.4
  • libvncserverDebian:14all versions · fixed in 0.9.11+dfsg-1.3

35 more package ranges on OSV.dev

Vendor advisories

  • CVE-2018-20748 Red Hat Product Security9 known affected

    libvncserver: Multiple heap out-of-bound writes in VNC client code (Incomplete fix for CVE-2018-20019)

    libvncserver as a component of Red Hat Enterprise Linux 6 · libvncserver-devel as a component of Red Hat Enterprise Linux 6 · libvncserver.src as a component of Red Hat Enterprise Linux 6 · +6 more

  • ICSA-21-350-12 CISA6 known affected

    Siemens SIMATIC ITC

    SIMATIC ITC1500 V3 · SIMATIC ITC1500 V3 PRO · SIMATIC ITC1900 V3 · +3 more

  • SSA-390195 Siemens ProductCERT6 known affected

    SSA-390195: LibVNC Vulnerabilities in SIMATIC ITC Products

    SIMATIC ITC1500 V3 · SIMATIC ITC1500 V3 PRO · SIMATIC ITC1900 V3 · +3 more

Full record on NVD

Fix

  1. Vendor fix Siemens ProductCERT SSA-390195 · 6 productsUpdate to V3.2.1.0 or later version
  2. Vendor fix CISA ICSA-21-350-12 · 6 productsUpdate to V3.2.1.0 or later version
  3. Mitigation from the vendor Siemens ProductCERT SSA-390195 · 6 productsMonitor and restrict access to port 5900/tcp to trusted IP addresses only
  4. Mitigation from the vendor CISA ICSA-21-350-12 · 6 productsMonitor and restrict access to port 5900/tcp to trusted IP addresses only
  5. No fix available, says the vendor Red Hat Product Security CVE-2018-20748 · 6 productsAffected
  6. No fix planned, says the vendor Red Hat Product Security CVE-2018-20748 · 3 productsWill not fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVSS 3.19.8read 2026-10-23
  • NVDCVSS 2.07.5read 2026-10-23
  • NVDweakness (CWE)CWE-787read 2026-10-23
  • FIRST EPSSEPSS score3.3 %2026-11-03
  • OSVaffected packages—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2019-01-30
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2018-20748?

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.

Is CVE-2018-20748 actively exploited?

Active exploitation of CVE-2018-20748 has not been confirmed. Its EPSS score was 3.3% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-20748?

CVE-2018-20748 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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