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Fencer Vulns
critical 9.8

CVE-2019-20788 json

libvncclient/cursor.c in LibVNCServer through 0.9.12 has a HandleCursorShape integer overflow and heap-based buffer overflow via a large he…

published 2020-04-23 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-11326

cvss
9.8
version 3.1, 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

libvncclient/cursor.c in LibVNCServer through 0.9.12 has a HandleCursorShape integer overflow and heap-based buffer overflow via a large height or width value. NOTE: this may overlap CVE-2019-15690.

Patch / fix

  • siemens simatic_itc1500_firmware 3.2.1.0
  • siemens simatic_itc1500_pro_firmware 3.2.1.0
  • siemens simatic_itc1900_firmware 3.2.1.0
  • siemens simatic_itc1900_pro_firmware 3.2.1.0
  • siemens simatic_itc2200_firmware 3.2.1.0
  • siemens simatic_itc2200_pro_firmware 3.2.1.0
  • libvncserver Debian 14, Debian 13, Debian 12 0.9.12+dfsg-9

debian advisories DEBIAN-CVE-2019-20788

  • libvncserver Ubuntu 16.04 LTS 0.9.10+dfsg-3ubuntu0.16.04.4
  • libvncserver Ubuntu 18.04 LTS 0.9.11+dfsg-1ubuntu1.2

ubuntu advisories UBUNTU-CVE-2019-20788

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 RHEL 8 0.9.11-9.el8_1.2
  • libvncserver RHEL 7 0.9.9-14.el7_7
  • libvncserver RHEL 8.0 E4S 0.9.11-9.el8_0.2

red hat advisories RHSA-2020:0921RHSA-2020:0920RHSA-2020:0913

  • LibVNCServer SLE Workstation Extension 15 SP1, SLE Module for Package Hub 15 SP1 0.9.10-4.14.1
  • LibVNCServer SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 0.9.1-160.14.1
  • LibVNCServer SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +16 more 0.9.9-17.19.1

suse advisories SUSE-SU-2020:1164-2SUSE-SU-2020:14355-1SUSE-SU-2020:1165-1SUSE-SU-2020:1164-1

  • LibVNCServer openSUSE Leap 15.1 0.9.10-lp151.7.3.1

opensuse advisories openSUSE-SU-2020:0624-1

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-2019-20788 updated cvss 0.0

libvncserver: integer overflow and heap-based buffer overflow in libvncclient/cursor.c in HandleCursorShape function

  • Red Hat CodeReady Linux Builder (v. 8) libvncserver 0.9.11-9.el8_1.2 Red Hat Enterprise Linux AppStream (v. 8) libvncserver 0.9.11-9.el8_1.2
    fixed: vendor fix RHSA-2020:0920
  • Red Hat Enterprise Linux AppStream E4S (v. 8.0) libvncserver 0.9.11-9.el8_0.2
    fixed: vendor fix RHSA-2020:0921
  • Red Hat Enterprise Linux Client (v. 7) libvncserver 0.9.9-14.el7_7 Red Hat Enterprise Linux Client Optional (v. 7) libvncserver-devel 0.9.9-14.el7_7, libvncserver-debuginfo 0.9.9-14.el7_7 Red Hat Enterprise Linux Server (v. 7) libvncserver 0.9.9-14.el7_7 Red Hat Enterprise Linux Server Optional (v. 7) libvncserver-devel 0.9.9-14.el7_7, libvncserver-debuginfo 0.9.9-14.el7_7 Red Hat Enterprise Linux Workstation (v. 7) libvncserver 0.9.9-14.el7_7 Red Hat Enterprise Linux Workstation Optional (v. 7) libvncserver-devel 0.9.9-14.el7_7, libvncserver-debuginfo 0.9.9-14.el7_7
    fixed: vendor fix RHSA-2020:0913
  • Red Hat Enterprise Linux 6 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

cisa ICSA-21-350-12 updated cvss 9.8

Siemens SIMATIC ITC

  • Siemens SIMATIC ITC1500 V3 <V3.2.1.0 Siemens SIMATIC ITC1500 V3 PRO <V3.2.1.0 Siemens SIMATIC ITC1900 V3 <V3.2.1.0 Siemens SIMATIC ITC1900 V3 PRO <V3.2.1.0 Siemens SIMATIC ITC2200 V3 <V3.2.1.0 Siemens SIMATIC ITC2200 V3 PRO <V3.2.1.0
    affected: fixed in V3.2.1.0, mitigation support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · 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).

Exploits and checks

  • securitylab.github.com https://securitylab.github.com/advisories/GHSL-2020-064-libvnc-libvncclient referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

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.