[USN-4616-1] AccountsService vulnerabilities

[Marc Deslauriers]

==========================================================================
Ubuntu Security Notice USN-4616-1
November 03, 2020

accountsservice vulnerabilities
==========================================================================

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

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in AccountsService.

Software Description:
- accountsservice: query and manipulate user account information

Details:

Kevin Backhouse discovered that AccountsService incorrectly dropped
privileges. A local user could possibly use this issue to cause
AccountsService to crash or hang, resulting in a denial of service.
(CVE-2020-16126)

Kevin Backhouse discovered that AccountsService incorrectly handled reading
.pam_environment files. A local user could possibly use this issue to cause
AccountsService to crash or hang, resulting in a denial of service. This
issue only affected Ubuntu 20.04 LTS and Ubuntu 20.10. (CVE-2020-16127)

Matthias Gerstner discovered that AccountsService incorrectly handled
certain path checks. A local attacker could possibly use this issue to
read arbitrary files. This issue only affected Ubuntu 16.04 LTS and Ubuntu
18.04 LTS. (CVE-2018-14036)

Update instructions:

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

Ubuntu 20.10:
  accountsservice                 0.6.55-0ubuntu13.2
  libaccountsservice0             0.6.55-0ubuntu13.2

Ubuntu 20.04 LTS:
  accountsservice                 0.6.55-0ubuntu12~20.04.4
  libaccountsservice0             0.6.55-0ubuntu12~20.04.4

Ubuntu 18.04 LTS:
  accountsservice                 0.6.45-1ubuntu1.3
  libaccountsservice0             0.6.45-1ubuntu1.3

Ubuntu 16.04 LTS:
  accountsservice                 0.6.40-2ubuntu11.6
  libaccountsservice0             0.6.40-2ubuntu11.6

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:
  https://usn.ubuntu.com/4616-1
  CVE-2018-14036, CVE-2020-16126, CVE-2020-16127

Package Information:
  https://launchpad.net/ubuntu/+source/accountsservice/0.6.55-0ubuntu13.2
  https://launchpad.net/ubuntu/+source/accountsservice/0.6.55-0ubuntu12~20.04.4
  https://launchpad.net/ubuntu/+source/accountsservice/0.6.45-1ubuntu1.3
  https://launchpad.net/ubuntu/+source/accountsservice/0.6.40-2ubuntu11.6

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