Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2018-20748

31
FAUCET Score

CVE-2018-20748 is a critical heap out-of-bounds write vulnerability affecting LibVNC versions prior to 0.9.12, specifically within the libvncclient/rfbproto.c component. This flaw, an incomplete fix for a previous vulnerability, impacts products from Canonical, Debian, LibVNC Project, and Siemens. With a CVSS score of 9.8 (Critical), it allows unauthenticated attackers to remotely execute code with high impact on confidentiality, integrity, and availability, requiring no user interaction. Despite its severity, there is no evidence of active exploitation, publicly available exploit code in Metasploit or ExploitDB, nor significant community discussion or 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:*:*:*:*:*:*:*
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:*:*:*
18.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.26%
Probability of exploitation in next 30 days
EPSS Percentile
87.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0326 is in the 79th percentile among its peer group of 36,833 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

github_advisorypatch availablevia nvd_reference
View patch
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: libvncserver
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: libvncserver
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: libvncserver

Vendor Advisories (1)

redhatCVE-2018-20748Moderate

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

Jan 6, 2019

References

cert-portal.siemens.com / productcert/pdf/ssa-390195.pdf
PatchThird Party Advisory
github.com / LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42bae
PatchThird Party Advisory
github.com / LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7
PatchThird Party Advisory
github.com / LibVNC/libvncserver/commit/c5ba3fee85a7ecbbca1df5ffd46d32b92757bc2a
PatchThird Party Advisory
github.com / LibVNC/libvncserver/commit/e34bcbb759ca5bef85809967a268fdf214c1ad2c
PatchThird Party Advisory
github.com / LibVNC/libvncserver/issues/273
Issue TrackingThird Party Advisory
lists.debian.org / debian-lts-announce/2019/01/msg00029.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2019/10/msg00042.html
Mailing ListThird Party Advisory
usn.ubuntu.com / 3877-1
Third Party Advisory
usn.ubuntu.com / 4547-1
Third Party Advisory
usn.ubuntu.com / 4587-1
Third Party Advisory
openwall.com / lists/oss-security/2018/12/10/8
ExploitMailing ListThird Party Advisory