CVE-2019-20788 is a critical-severity flaw (CVSS 9.8) affecting libvncserver, ubuntu linux, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
canonical ubuntu linux MITIGATE
Affected: 14.04 · 16.04 · 18.04 · 18.10
Fixed in: no fixed release known
Safe to downgrade to: a release before 14.04
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
debian debian linux MITIGATE
Affected: 8.0 · 9.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 8.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
siemens simatic itc1500 firmware UPGRADE
Affected: >= 3.0.0.0 and < 3.2.1.0
Fixed in: 3.2.1.0
Safe to downgrade to: a release before 3.0.0.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
siemens simatic itc1500 pro firmware UPGRADE
Affected: >= 3.0.0.0 and < 3.2.1.0
Fixed in: 3.2.1.0
Safe to downgrade to: a release before 3.0.0.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
siemens simatic itc1900 firmware UPGRADE
Affected: >= 3.0.0.0 and < 3.2.1.0
Fixed in: 3.2.1.0
Safe to downgrade to: a release before 3.0.0.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Verify at the official sourceNVD · CVE Program · Report a problem with this page Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2019-20788?
libvncserver: upgrade to newer than 0.9.12; ubuntu linux: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2019-20788 being exploited?
CVE-2019-20788 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2019-20788 affect?
CVE-2019-20788 affects libvncserver, ubuntu linux, debian linux. Severity is critical (CVSS 9.8). 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.
How urgent is CVE-2019-20788?
Priority 70/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist
PatchTheCVE