Synopsis

Low: openssh security, bug fix, and enhancement update

Type/Severity

Security Advisory: Low

Topic

An update for openssh is now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having a security impact of Low. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

OpenSSH is an SSH protocol implementation supported by a number of Linux, UNIX, and similar operating systems. It includes the core files necessary for both the OpenSSH client and server.

Security Fix(es):

• openssh: Improper write operations in readonly mode allow for zero-length file creation (CVE-2017-15906)

For more details about the security issue(s), including the impact, a CVSS score, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 7.5 Release Notes linked from the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

After installing this update, the OpenSSH server daemon (sshd) will be restarted automatically.

Affected Products

• Red Hat Enterprise Linux Server 7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 x86_64
• Red Hat Enterprise Linux for Power, little endian 7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.6 ppc64le
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux for ARM 64 7 aarch64
• Red Hat Enterprise Linux for Power 9 7 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.7 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.6 ppc64le
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux for IBM System z (Structure A) 7 s390x

Fixes

• BZ - 1456853 - ssh -Q and -G list host key types that are not allowed in FIPS mode
• BZ - 1478175 - The UseDNS configuration option changed default behaviour between 7.3 and 7.4, this breaks existing configurations until manually corrected
• BZ - 1480510 - SSH connections get closed when time-based rekeyring is used and ClientAliveMaxCount=0
• BZ - 1488083 - segfaults when cleaning up session due to some error
• BZ - 1488982 - GSSAPIStrictAcceptorCheck default change with 7.4
• BZ - 1494268 - pam_ssh_agent_auth SEGV's if keyfile is missing
• BZ - 1496467 - Regression: SSH AuthorizedKeysCommand hangs when output is too large
• BZ - 1496808 - OpenSSH 7.4 doesn't work with WinSCP >= 5.10 clients
• BZ - 1506630 - CVE-2017-15906 openssh: Improper write operations in readonly mode allow for zero-length file creation

CVEs

• CVE-2017-15906

References