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Fencer Vulns
high 7.5

CVE-2018-20023 json

LibVNC before 8b06f835e259652b0ff026898014fc7297ade858 contains CWE-665: Improper Initialization vulnerability in VNC Repeater client code…

published 2018-12-19 7 y ago modified 2026-06-17 4 mo ago also EUVD-2018-12601

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.5%
EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

LibVNC before 8b06f835e259652b0ff026898014fc7297ade858 contains CWE-665: Improper Initialization vulnerability in VNC Repeater client code that allows attacker to read stack memory and can be abuse for information disclosure. Combined with another vulnerability, it can be used to leak stack memory layout and in bypassing ASLR

Patch / fix

  • libvnc_project libvncserver 0.9.12
  • veyon Debian 13, Debian 12 4.1.4+repack1-1
  • libvncserver Debian 14, Debian 13, Debian 12 0.9.11+dfsg-1.2

debian advisories DEBIAN-CVE-2018-20023

  • italc Ubuntu 16.04 LTS 1:2.0.2+dfsg1-4ubuntu0.1
  • italc Ubuntu 18.04 LTS 1:3.0.3+dfsg1-3ubuntu0.1
  • libvncserver Ubuntu 14.04 LTS 0.9.9+dfsg-1ubuntu1.4
  • libvncserver Ubuntu 16.04 LTS 0.9.10+dfsg-3ubuntu0.16.04.3
  • libvncserver Ubuntu 18.04 LTS 0.9.11+dfsg-1ubuntu1.1

ubuntu advisories UBUNTU-CVE-2018-20023

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • LibVNCServer SLES 12 SP4, SLES 12 SP3, SLES 12 SP2-BCL +11 more 0.9.9-17.8.1
  • LibVNCServer SLE Workstation Extension 15, SLE Module for Package Hub 15 0.9.10-4.3.1

suse advisories SUSE-SU-2019:0060-2SUSE-SU-2019:0080-1SUSE-SU-2019:0060-1

  • LibVNCServer openSUSE Leap 15.0 0.9.10-lp150.3.3.1

opensuse advisories openSUSE-SU-2019:0053-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-20023 updated cvss 4.3

libvncserver: Improper initialization in VNC Repeater client code allows for information disclosure

  • Red Hat Enterprise Linux 8 libvncserver
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 6 libvncserver Red Hat Enterprise Linux 7 libvncserver
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.50% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Affected products

  • n/a LibVNC

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.