A Caribou security update has been released for Ubuntu Linux 20.04 LTS and 20.10.

USN-4958-1: Caribou vulnerability

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Ubuntu Security Notice USN-4958-1
May 17, 2021

caribou vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10
- Ubuntu 20.04 LTS

Summary:

Applications using Caribou could be made to crash if given specially
crafted input.

Software Description:
- caribou: Configurable on screen keyboard with scanning mode

Details:

It was discovered that the Caribou onscreen keyboard could be made
to crash when given certain input values. An attacker could use this
to bypass screen-locking applications that support using Caribou as
an input mechanism.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 20.10:
gir1.2-caribou-1.0 0.4.21-7ubuntu0.20.10.1
libcaribou0 0.4.21-7ubuntu0.20.10.1

Ubuntu 20.04 LTS:
gir1.2-caribou-1.0 0.4.21-7ubuntu0.20.04.1
libcaribou0 0.4.21-7ubuntu0.20.04.1

After a standard system update you need to restart applications that
use Caribou as an onscreen keyboard to make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-4958-1
  https://launchpad.net/bugs/1912060

Package Information:
  https://launchpad.net/ubuntu/+source/caribou/0.4.21-7ubuntu0.20.10.1
  https://launchpad.net/ubuntu/+source/caribou/0.4.21-7ubuntu0.20.04.1