postgresql-9.6 security update

ackage        : postgresql-9.6
CVE ID         : CVE-2017-7546 CVE-2017-7547 CVE-2017-7548

Several vulnerabilities have been found in the PostgreSQL database
system:

CVE-2017-7546

    In some authentication methods empty passwords were accepted.

CVE-2017-7547

    User mappings could leak data to unprivileged users.

CVE-2017-7548

    The lo_put() function ignored ACLs.

For more in-depth descriptions of the security vulnerabilities,
please see https://www.postgresql.org/about/news/1772/

For the stable distribution (stretch), these problems have been fixed in
version 9.6.4-0+deb9u1.

We recommend that you upgrade your postgresql-9.6 packages.

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/