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CVE-2018-20023

25
FAUCET Score

CVE-2018-20023 is an Improper Initialization vulnerability (CWE-665) in LibVNC before version 8b06f835e259652b0ff026898014fc7297ade858, affecting various Canonical and Debian Linux distributions and their LibVNCServer packages. This vulnerability allows an unauthenticated attacker to read stack memory, potentially leading to information disclosure and, when combined with other vulnerabilities, could bypass ASLR. It carries a CVSSv3 score of 7.5 (High), indicating a network-exploitable vulnerability with low attack complexity and high confidentiality impact. While there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB) is unavailable, and community discussion is limited, though it has received some media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.9.12CPE matchmatch criteria
cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*
8.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
14.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
16.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
2.50%
Probability of exploitation in next 30 days
EPSS Percentile
83.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0249 is in the 70th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: libvncserver

Vendor Advisories (1)

redhatCVE-2018-20023Low

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

Dec 19, 2018

References

ics-cert.kaspersky.com / advisories/klcert-advisories/2018/12/19/klcert-18-033-libvnc-memory-leak
Third Party Advisory
lists.debian.org / debian-lts-announce/2018/12/msg00017.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2019/10/msg00042.html
security.gentoo.org / glsa/201908-05
usn.ubuntu.com / 3877-1
Third Party Advisory
usn.ubuntu.com / 4547-1
usn.ubuntu.com / 4587-1
debian.org / security/2019/dsa-4383
Third Party Advisory