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CVE-2018-20019

35
FAUCET Score

CVE-2018-20019 is a critical heap out-of-bounds write vulnerability in LibVNC client code, affecting products from Canonical, Debian, LibVNC Project, and Siemens. With a CVSS score of 9.8, it allows unauthenticated remote attackers to achieve remote code execution with low attack complexity. While no public exploit code or active exploitation has been confirmed, the vulnerability has garnered significant community discussion and media coverage, indicating awareness of its severe potential impact.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.9.12CPE matchmatch criteria
cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*
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:*:*:*:esm:*:*:*
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
9.47%
Probability of exploitation in next 30 days
EPSS Percentile
94.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0947 is in the 90th percentile among its peer group of 36,829 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

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

Remediation

Vendor Patches (3)

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-2018-20019Moderate

libvncserver: Multiple heap out-of-bound writes in VNC client code

Dec 19, 2018

References

cert-portal.siemens.com / productcert/pdf/ssa-390195.pdf
PatchThird Party Advisory
ics-cert.kaspersky.com / advisories/klcert-advisories/2018/12/19/klcert-18-029-libvnc-multiple-heap-out-of-bound-vulnerabilities
Broken Link
lists.debian.org / debian-lts-announce/2018/12/msg00017.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2019/10/msg00042.html
Mailing ListThird Party Advisory
security.gentoo.org / glsa/201908-05
Third 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
debian.org / security/2019/dsa-4383
Third Party Advisory