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

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 packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es) :

* Modern operating systems implement virtualization of physical memory to efficiently use available system resources and provide inter-domain protection through access control and isolation. The L1TF issue was found in the way the x86 microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimisation) in combination with handling of page-faults caused by terminated virtual to physical address resolving process. As a result, an unprivileged attacker could use this flaw to read privileged memory of the kernel or other processes and/or cross guest/host boundaries to read host memory by conducting targeted cache side-channel attacks.
(CVE-2018-3620, CVE-2018-3646)

* An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions past bounds check. The flaw relies on the presence of a precisely-defined instruction sequence in the privileged code and the fact that memory writes occur to an address which depends on the untrusted value. Such writes 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 influence speculative execution and/or read privileged memory by conducting targeted cache side-channel attacks.
(CVE-2018-3693)

* 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.
(CVE-2018-5390)

* kernel: crypto: privilege escalation in skcipher_recvmsg function (CVE-2017-13215)

* kernel: mm: use-after-free in do_get_mempolicy function allows local DoS or other unspecified impact (CVE-2018-10675)

* kernel: race condition in snd_seq_write() may lead to UAF or OOB access (CVE-2018-7566)

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 Intel OSSIRT (Intel.com) for reporting CVE-2018-3620 and CVE-2018-3646; Vladimir Kiriansky (MIT) and Carl Waldspurger (Carl Waldspurger Consulting) for reporting CVE-2018-3693;
and Juha-Matti Tilli (Aalto University, Department of Communications and Networking and Nokia Bell Labs) for reporting CVE-2018-5390.

Bug Fix(es) :

These updated kernel packages include also numerous bug fixes. Space precludes documenting all of the bug fixes in this advisory. See the descriptions in the related Knowledge Article :

https://access.redhat.com/articles/3527791

The remote Redhat Enterprise Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2018:2948 advisory.

    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. (CVE-2018-5390)

    * 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:

    https://access.redhat.com/articles/3658021

    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.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Published	Updated	Severity
111703	CentOS 7 : kernel (CESA-2018:2384) (Foreshadow)	Nessus	CentOS Local Security Checks	8/15/2018	8/21/2024	high
118513	RHEL 7 : kernel-alt (RHSA-2018:2948)	Nessus	Red Hat Local Security Checks	10/31/2018	1/9/2026	high

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