Xen PV guest before Xen 4.3 checked access permissions to MMIO ranges only after accessing them, allowing host PCI device space memory reads, leading to information disclosure. This is an error in the get_user function. NOTE: the upstream Xen Project considers versions before 4.5.x to be EOL.

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

  - Xen PV guest before Xen 4.3 checked access permissions to MMIO ranges only after accessing them, allowing     host PCI device space memory reads, leading to information disclosure. This is an error in the get_user     function. NOTE: the upstream Xen Project considers versions before 4.5.x to be EOL. (CVE-2017-7995)

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

Multiple vulnerabilities have been discovered in the Xen hypervisor.
The Common Vulnerabilities and Exposures project identifies the following problems :

CVE-2016-9932 (XSA-200)

CMPXCHG8B emulation allows local HVM guest OS users to obtain sensitive information from host stack memory.

CVE-2017-7995

Description Xen checks access permissions to MMIO ranges only after accessing them, allowing host PCI device space memory reads.

CVE-2017-8903 (XSA-213)

Xen mishandles page tables after an IRET hypercall which can lead to arbitrary code execution on the host OS. The vulnerability is only exposed to 64-bit PV guests.

CVE-2017-8904 (XSA-214)

Xen mishandles the 'contains segment descriptors' property during GNTTABOP_transfer. This might allow PV guest OS users to execute arbitrary code on the host OS.

CVE-2017-8905 (XSA-215)

Xen mishandles a failsafe callback which might allow PV guest OS users to execute arbitrary code on the host OS.

For Debian 7 'Wheezy', these problems have been fixed in version 4.1.6.lts1-8.

We recommend that you upgrade your xen packages.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for xen fixes several security issues :

  - A malicious 64-bit PV guest may be able to access all of     system memory, allowing for all of privilege escalation,     host crashes, and information leaks by placing a IRET     hypercall in the middle of a multicall batch (XSA-213,     bsc#1034843)

  - A malicious pair of guests may be able to access all of     system memory, allowing for all of privilege escalation,     host crashes, and information leaks because of a missing     check when transfering pages via GNTTABOP_transfer     (XSA-214, bsc#1034844).

  - CVE-2017-7718: hw/display/cirrus_vga_rop.h allowed local     guest OS privileged users to cause a denial of service     (out-of-bounds read and QEMU process crash) via vectors     related to copying VGA data via the     cirrus_bitblt_rop_fwd_transp_ and cirrus_bitblt_rop_fwd_     functions (bsc#1034994).

  - CVE-2016-9603: A privileged user within the guest VM     could have caused a heap overflow in the device model     process, potentially escalating their privileges to that     of the device model process (bsc#1028655)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
221675	Linux Distros Unpatched Vulnerability : CVE-2017-7995	Nessus	Misc.	low
100575	Debian DLA-964-1 : xen security update	Nessus	Debian Local Security Checks	high
99961	SUSE SLES11 Security Update : xen (SUSE-SU-2017:1146-1)	Nessus	SuSE Local Security Checks	critical

Detections

Analytics

CVE-2017-7995

low

Tenable Plugins

low

high

critical