A stack-based buffer overflow vulnerability was found in NBD server implementation in qemu before 2.11 allowing a client to request an export name of size up to 4096 bytes, which in fact should be limited to 256 bytes, causing an out-of-bounds stack write in the qemu process. If NBD server requires TLS, the attacker cannot trigger the buffer overflow without first successfully negotiating TLS.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - A stack-based buffer overflow vulnerability was found in NBD server implementation in qemu before 2.11     allowing a client to request an export name of size up to 4096 bytes, which in fact should be limited to     256 bytes, causing an out-of-bounds stack write in the qemu process. If NBD server requires TLS, the     attacker cannot trigger the buffer overflow without first successfully negotiating TLS. (CVE-2017-15118)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote Redhat Enterprise Linux 7 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2018:1104 advisory.

    KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on a variety of     architectures. The qemu-kvm-rhev packages provide the user-space component for running virtual machines     that use KVM in environments managed by Red Hat products.

    The following packages have been upgraded to a later upstream version: qemu-kvm-rhev (2.10.0).
    (BZ#1470749)

    Security Fix(es):

    * Qemu: stack buffer overflow in NBD server triggered via long export name (CVE-2017-15118)

    * Qemu: DoS via large option request (CVE-2017-15119)

    * Qemu: vga: OOB read access during display update (CVE-2017-13672)

    * Qemu: vga: reachable assert failure during display update (CVE-2017-13673)

    * Qemu: Slirp: use-after-free when sending response (CVE-2017-13711)

    * Qemu: memory exhaustion through framebuffer update request message in VNC server (CVE-2017-15124)

    * Qemu: I/O: potential memory exhaustion via websock connection to VNC (CVE-2017-15268)

    * Qemu: Out-of-bounds read in vga_draw_text routine (CVE-2018-5683)

    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 David Buchanan for reporting CVE-2017-13672 and CVE-2017-13673; Wjjzhang     (Tencent.com) for reporting CVE-2017-13711; and Jiang Xin and Lin ZheCheng for reporting CVE-2018-5683.
    The CVE-2017-15118 and CVE-2017-15119 issues were discovered by Eric Blake (Red Hat) and the     CVE-2017-15124 issue was discovered by Daniel Berrange (Red Hat).

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.

The remote Ubuntu 14.04 LTS / 16.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-3575-1 advisory.

    It was discovered that QEMU incorrectly handled guest ram. A privileged attacker inside the guest could     use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected Ubuntu     14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-11334)

    David Buchanan discovered that QEMU incorrectly handled the VGA device. A privileged attacker inside the     guest could use this issue to cause QEMU to crash, resulting in a denial of service. This issue was only     addressed in Ubuntu 17.10. (CVE-2017-13672)

    Thomas Garnier discovered that QEMU incorrectly handled multiboot. An attacker could use this issue to     cause QEMU to crash, resulting in a denial of service, or possibly execute arbitrary code on the host. In     the default installation, when QEMU is used with libvirt, attackers would be isolated by the libvirt     AppArmor profile. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-14167)

    Tuomas Tynkkynen discovered that QEMU incorrectly handled VirtFS directory sharing. An attacker could use     this issue to obtain sensitive information from host memory. (CVE-2017-15038)

    Eric Blake discovered that QEMU incorrectly handled memory in the NBD server. An attacker could use this     issue to cause the NBD server to crash, resulting in a denial of service. This issue only affected Ubuntu     17.10. (CVE-2017-15118)

    Eric Blake discovered that QEMU incorrectly handled certain options to the NBD server. An attacker could     use this issue to cause the NBD server to crash, resulting in a denial of service. This issue only     affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-15119)

    Daniel Berrange discovered that QEMU incorrectly handled the VNC server. A remote attacker could possibly     use this issue to consume memory, resulting in a denial of service. This issue was only addressed in     Ubuntu 17.10. (CVE-2017-15124)

    Carl Brassey discovered that QEMU incorrectly handled certain websockets. A remote attacker could possibly     use this issue to consume memory, resulting in a denial of service. This issue only affected Ubuntu 17.10.
    (CVE-2017-15268)

    Guoxiang Niu discovered that QEMU incorrectly handled the Cirrus VGA device. A privileged attacker inside     the guest could use this issue to cause QEMU to crash, resulting in a denial of service. (CVE-2017-15289)

    Cyrille Chatras discovered that QEMU incorrectly handled certain PS2 values during migration. An attacker     could possibly use this issue to cause QEMU to crash, resulting in a denial of service, or possibly     execute arbitrary code. This issue only affected Ubuntu 16.04 LTS and Ubuntu 17.10. (CVE-2017-16845)

    It was discovered that QEMU incorrectly handled the Virtio Vring implementation. An attacker could     possibly use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected     Ubuntu 16.04 LTS and Ubuntu 17.10. (CVE-2017-17381)

    Eric Blake discovered that QEMU incorrectly handled certain rounding operations. An attacker could     possibly use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected     Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-18043)

    Jiang Xin and Lin ZheCheng discovered that QEMU incorrectly handled the VGA device. A privileged attacker     inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service.
    (CVE-2018-5683)

Tenable has extracted the preceding description block directly from the Ubuntu 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	Severity
220642	Linux Distros Unpatched Vulnerability : CVE-2017-15118	Nessus	Misc.	critical
109070	RHEL 7 : qemu-kvm-rhev (RHSA-2018:1104)	Nessus	Red Hat Local Security Checks	critical
106927	Ubuntu 14.04 LTS / 16.04 LTS : QEMU vulnerabilities (USN-3575-1)	Nessus	Ubuntu Local Security Checks	critical

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CVE-2017-15118

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