CVE-2019-7306: 
Linux Debian vulnerability analysis and mitigation

CVE-2019-7306 is a security vulnerability in the Byobu package, discovered by Sander Bos in 2019. The vulnerability affects the Apport hook functionality in Byobu, which could potentially expose sensitive information by automatically uploading the user's .screenrc file containing private hostnames, usernames, and passwords (Ubuntu Security, NVD).

The vulnerability exists in the Byobu Apport hook file (debian/source_byobu.py) which automatically includes the user's ~/.screenrc file in crash reports. The issue was introduced in Byobu version 2.20-0ubuntu1, released on 2009-07-12. The vulnerability has a CVSS 3.1 Base Score of 7.5 (High) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N (Ubuntu Security).

The vulnerability could lead to the disclosure of sensitive information including passwords, usernames, and hostnames stored in the user's .screenrc file. This information could be exposed when crash reports are automatically uploaded to external bug databases without user intervention (Launchpad Bug).

The vulnerability requires specific conditions to be exploitable: the system must have Apport framework installed and enabled, Byobu needs to crash or a bug report needs to be manually created, and the crash report must be uploaded to an external bug database. The exploitation can occur either through regular application usage or potentially through malicious actions causing the application to crash (Launchpad Bug).

The immediate workaround is to remove the Byobu package Apport hook file from the system at /usr/share/apport/package-hooks/source_byobu.py. A permanent fix was implemented in version 5.128-0ubuntu1 for Ubuntu Eoan, which removes the inclusion of the .screenrc file from crash reports. For Ubuntu 16.04 LTS, the fix is available in version 5.106-0ubuntu1+esm1 (Ubuntu Security Notice).