SynopsisThe remote Red Hat host is missing one or more security updates.
DescriptionAn update for kernel-alt is now available for Red Hat Enterprise Linux
Red Hat Product Security has rated this update as having a security
impact of Important. 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.
The kernel-alt packages provide the Linux kernel version 4.x.
Security Fix(es) :
* An industry-wide issue was found in the way many modern
microprocessor designs have implemented speculative execution of Load
& Store instructions (a commonly used performance optimization). It
relies on the presence of a precisely-defined instruction sequence in
the privileged code as well as the fact that memory read from address
to which a recent memory write has occurred may see an older value and
subsequently cause an update into the microprocessor's data cache even
for speculatively executed instructions that never actually commit
(retire). As a result, an unprivileged attacker could use this flaw to
read privileged memory by conducting targeted cache side-channel
attacks. (CVE-2018-3639, aarch64)
* A flaw named SegmentSmack was found in the way the Linux kernel
handled specially crafted TCP packets. A remote attacker could use
this flaw to trigger time and calculation expensive calls to
tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() functions by
sending specially modified packets within ongoing TCP sessions which
could lead to a CPU saturation and hence a denial of service on the
system. Maintaining the denial of service condition requires
continuous two-way TCP sessions to a reachable open port, thus the
attacks cannot be performed using spoofed IP addresses.
* A flaw named FragmentSmack was found in the way the Linux kernel
handled reassembly of fragmented IPv4 and IPv6 packets. A remote
attacker could use this flaw to trigger time and calculation expensive
fragment reassembly algorithm by sending specially crafted packets
which could lead to a CPU saturation and hence a denial of service on
the system. (CVE-2018-5391)
Space precludes documenting all of the security fixes in this
advisory. See the descriptions of the remaining security fixes in the
related Knowledge Article :
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.
Red Hat would like to thank Ken Johnson (Microsoft Security Response
Center) and Jann Horn (Google Project Zero) for reporting
CVE-2018-3639; Juha-Matti Tilli (Aalto University - Department of
Communications and Networking and Nokia Bell Labs) for reporting
CVE-2018-5390 and CVE-2018-5391; Qualys Research Labs for reporting
CVE-2018-1120; David Rientjes (Google) for reporting CVE-2018-1000200;
and Wen Xu for reporting CVE-2018-1092, CVE-2018-1094, and
CVE-2018-1095. The CVE-2018-14619 issue was discovered by Florian
Weimer (Red Hat) and Ondrej Mosnacek (Red Hat).
Additional Changes :
For detailed information on changes in this release, see the Red Hat
Enterprise Linux 7.6 Release Notes linked from the References section.
SolutionUpdate the affected packages.