Ubuntu focal updates x11vnc to fix CVE-2020-29074

CVE-2020-29074

Ubuntu has released a fix for CVE-2020-29074 in x11vnc on Ubuntu focal. The vulnerability involves insecure permissions on shared memory areas and could let a local attacker obtain sensitive information or modify screen contents. Update to the fixed version and restart x11vnc.

At a glance
Ubuntu focal has a fix for CVE-2020-29074 in x11vnc.
A local attacker could obtain sensitive information or modify screen contents.
Fixed version: 0.9.16-3ubuntu0.1~esm2 from the esm-apps pocket.
Update the package and restart x11vnc to apply the change.

In this article

Ubuntu has published an advisory for a fix to CVE-2020-29074 in x11vnc on Ubuntu focal. Administrators can consult the USN-9089-1 security notice for details.

Overview and technical details

x11vnc allows remote access to and control of an X11 screen over VNC. CVE-2020-29074 concerns insecure permissions on shared memory areas created by x11vnc.

Field	Details
Product	x11vnc on Ubuntu focal
Vulnerability	CVE-2020-29074
Source	Ubuntu USN-9089-1

Affected systems

The advisory identifies the x11vnc package on Ubuntu focal. Version 0.9.16-3ubuntu0.1~esm2 from the esm-apps pocket is fixed; according to the source's checking guidance, earlier versions need an update.

Product	Fixed version	Pocket
x11vnc on Ubuntu focal	0.9.16-3ubuntu0.1~esm2	esm-apps

Mechanism and impact

x11vnc creates shared memory areas with insecure permissions. A local attacker could exploit the vulnerability to obtain sensitive information or modify screen contents.

System checks

On Ubuntu focal, check the installed x11vnc version and package information with these commands:
```
dpkg-query -W -f='${Version}\n' x11vnc
apt-cache policy x11vnc
pro status
```
Compare the installed version: 0.9.16-3ubuntu0.1~esm2 or later is fixed; an earlier version needs an update.

Remediation and mitigation

Use the standard system update process to install x11vnc version 0.9.16-3ubuntu0.1~esm2 from the esm-apps pocket.
After updating, restart x11vnc to apply the changes fully.

References: Ubuntu USN