Xen 4.5.x and earlier enables certain default backends when emulating a VGA device for an x86 HVM guest qemu even when the configuration disables them, which allows local guest users to obtain access to the VGA console by (1) setting the DISPLAY environment variable, when compiled with SDL support, or connecting to the VNC server on (2) ::1 or (3) 127.0.0.1, when not compiled with SDL support.

The remote OracleVM system is missing necessary patches to address critical security updates : please see Oracle VM Security Advisory OVMSA-2020-0039 for details.

The remote OracleVM system is missing necessary patches to address critical security updates : please see Oracle VM Security Advisory OVMSA-2018-0248 for details.

The remote OracleVM system is missing necessary patches to address critical security updates : please see Oracle VM Security Advisory OVMSA-2015-0096 for details.

The remote OracleVM system is missing necessary patches to address critical security updates :

  - ide: Clear DRQ after handling all expected accesses This     is additional hardening against an end_transfer_func     that fails to clear the DRQ status bit. The bit must be     unset as soon as the PIO transfer has completed, so it's     better to do this in a central place instead of     duplicating the code in all commands (and forgetting it     in some).

    This is XSA-138 CVE-2015-5154 (CVE-2015-5154)

  - ide/atapi: Fix START STOP UNIT command completion The     command must be completed on all code paths. START STOP     UNIT with pwrcnd set should succeed without doing     anything.

    This is XSA-138 CVE-2015-5154 (CVE-2015-5154)

  - ide: Check array bounds before writing to io_buffer     (CVE-2015-5154) If the end_transfer_func of a command is     called because enough data has been read or written for     the current PIO transfer, and it fails to correctly call     the command completion functions, the DRQ bit in the     status register and s->end_transfer_func may remain set.
    This allows the guest to access further bytes in     s->io_buffer beyond s->data_end, and eventually     overflowing the io_buffer. One case where this currently     happens is emulation of the ATAPI command START STOP     UNIT. This patch fixes the problem by adding explicit     array bounds checks before accessing the buffer instead     of relying on end_transfer_func to function correctly.
    Cc :

    This is XSA-138 (CVE-2015-5154)

  - ide: Clear DRQ after handling all expected accesses This     is additional hardening against an end_transfer_func     that fails to clear the DRQ status bit. The bit must be     unset as soon as the PIO transfer has completed, so it's     better to do this in a central place instead of     duplicating the code in all commands (and forgetting it     in some).

    This is XSA-138 (CVE-2015-5154)

  - ide: Check array bounds before writing to io_buffer If     the end_transfer_func of a command is called because     enough data has been read or written for the current PIO     transfer, and it fails to correctly call the command     completion functions, the DRQ bit in the status register     and s->end_transfer_func may remain set. This allows the     guest to access further bytes in s->io_buffer beyond     s->data_end, and eventually overflowing the io_buffer.
    One case where this currently happens is emulation of     the ATAPI command START STOP UNIT. This patch fixes the     problem by adding explicit array bounds checks before     accessing the buffer instead of relying on     end_transfer_func to function correctly. Cc :

    This is XSA-138 (CVE-2015-5154)

  - tools: libxl: Explicitly disable graphics backends on     qemu cmdline By default qemu will try to create some     sort of backend for the emulated VGA device, either SDL     or VNC. However when the user specifies sdl=0 and vnc=0     in their configuration libxl was not explicitly     disabling either backend, which could lead to one     unexpectedly running. If either sdl=1 or vnc=1 is     configured then both before and after this change only     the backends which are explicitly enabled are     configured, i.e. this issue only occurs when all     backends are supposed to have been disabled. This     affects qemu-xen and qemu-xen-traditional differently.
    If qemu-xen was compiled with SDL support then this     would result in an SDL window being opened if $DISPLAY     is valid, or a failure to start the guest if not.
    Passing '-display none' to qemu before any further

    -sdl options disables this default behaviour and ensures     that SDL is only started if the libxl configuration     demands it. If qemu-xen was compiled without SDL support     then qemu would instead start a VNC server listening on     ::1 (IPv6 localhost) or 127.0.0.1 (IPv4 localhost) with     IPv6 preferred if available. Explicitly pass '-vnc none'     when vnc is not enabled in the libxl configuration to     remove this possibility. qemu-xen-traditional would     never start a vnc backend unless asked. However by     default it will start an SDL backend, the way to disable     this is to pass a -vnc option. In other words passing     '-vnc none' will disable both vnc and sdl by default.
    sdl can then be reenabled if configured by subsequent     use of the -sdl option. Tested with both qemu-xen and     qemu-xen-traditional built with SDL support and: xl cr #     defaults xl cr sdl=0 vnc=0 xl cr sdl=1 vnc=0 xl cr sdl=0     vnc=1 xl cr sdl=0 vnc=0 vga='none' xl cr sdl=0 vnc=0     nographic=1 with both valid and invalid $DISPLAY. This     is XSA-119 / CVE-2015-2152. (CVE-2015-2152)

The Xen Project reports :

When instantiating an emulated VGA device for an x86 HVM guest qemu will by default enable a backend to expose that device, either SDL or VNC depending on the version of qemu and the build time configuration.

The libxl toolstack library does not explicitly disable these default backends when they are not enabled, leading to an unexpected backend running.

If either SDL or VNC is explicitly enabled in the guest configuration then only the expected backends will be enabled.

This affects qemu-xen and qemu-xen-traditional differently.

If qemu-xen was compiled with SDL support then this would result in an SDL window being opened if $DISPLAY is valid, or a failure to start the guest if not.

If qemu-xen was compiled without SDL support then qemu would instead start a VNC server listening on ::1 (IPv6 localhost) or 127.0.0.1 (IPv4 localhost) with IPv6 preferred if available. A VNC password will not be configured even if one is present in the guest configuration.

qemu-xen-traditional will never start a vnc backend unless explicitly configured. However by default it will start an SDL backend if it was built with SDL support and $DISPLAY is valid.

Xen was updated to 4.4.2 to fix multiple vulnerabilities and non-security bugs.

The following vulnerabilities were fixed :

  - CVE-2015-4103: Potential unintended writes to host MSI     message data field via qemu (XSA-128) (boo#931625)

  - CVE-2015-4104: PCI MSI mask bits inadvertently exposed     to guests (XSA-129) (boo#931626)

  - CVE-2015-4105: Guest triggerable qemu MSI-X pass-through     error messages (XSA-130) (boo#931627)

  - CVE-2015-4106: Unmediated PCI register access in qemu     (XSA-131) (boo#931628)

  - CVE-2015-4164: DoS through iret hypercall handler     (XSA-136) (boo#932996)

  - CVE-2015-4163: GNTTABOP_swap_grant_ref operation     misbehavior (XSA-134) (boo#932790)

  - CVE-2015-3209: heap overflow in qemu pcnet controller     allowing guest to host escape (XSA-135) (boo#932770)

  - CVE-2015-3456: Fixed a buffer overflow in the floppy     drive emulation, which could be used to denial of     service attacks or potential code execution against the     host. ()

  - CVE-2015-3340: Xen did not initialize certain fields,     which allowed certain remote service domains to obtain     sensitive information from memory via a (1)     XEN_DOMCTL_gettscinfo or (2)     XEN_SYSCTL_getdomaininfolist request. ()

  - CVE-2015-2752: Long latency MMIO mapping operations are     not preemptible (XSA-125 boo#922705)

  - CVE-2015-2756: Unmediated PCI command register access in     qemu (XSA-126 boo#922706)

  - CVE-2015-2751: Certain domctl operations may be abused     to lock up the host (XSA-127 boo#922709)

  - CVE-2015-2151: Hypervisor memory corruption due to x86     emulator flaw (boo#919464 XSA-123)

  - CVE-2015-2045: Information leak through version     information hypercall (boo#918998 XSA-122)

  - CVE-2015-2044: Information leak via internal x86 system     device emulation (boo#918995 (XSA-121)

  - CVE-2015-2152: HVM qemu unexpectedly enabling emulated     VGA graphics backends (boo#919663 XSA-119)

  - CVE-2014-3615: information leakage when guest sets high     resolution (boo#895528)

The following non-security bugs were fixed :

  - xentop: Fix memory leak on read failure 

  - boo#923758: xen dmesg contains bogus output in early     boot

  - boo#921842: Xentop doesn't display disk statistics for     VMs using qdisks

  - boo#919098: L3: XEN blktap device intermittently fails     to connect 

  - boo#882089: Windows 2012 R2 fails to boot up with     greater than 60 vcpus

  - boo#903680: Problems with detecting free loop devices on     Xen guest startup

  - boo#861318: xentop reports 'Found interface vif101.0 but     domain 101 does not exist.'

  - boo#901488: Intel ixgbe driver assigns rx/tx queues per     core resulting in irq problems on servers with a large     amount of CPU cores

  - boo#910254: SLES11 SP3 Xen VT-d igb NIC doesn't work

  - boo#912011: high ping latency after upgrade to latest     SLES11SP3 on xen Dom0

  - boo#906689: let systemd schedule xencommons after     network-online.target and remote-fs.target so that     xendomains has access to remote shares

The following functionality was enabled or enhanced :

  - Enable spice support in qemu for x86_64

  - Add Qxl vga support

  - Enhancement to virsh/libvirtd 'send-key' command     (FATE#317240)

  - Add domain_migrate_constraints_set API to Xend's http     interface (FATE#317239)

The XEN hypervisor received updates to fix various security issues and bugs.

The following security issues were fixed :

  - CVE-2015-2151: XSA-123: A hypervisor memory corruption     due to x86 emulator flaw.

  - CVE-2015-2045: XSA-122: Information leak through version     information hypercall.

  - CVE-2015-2044: XSA-121: Information leak via internal     x86 system device emulation.

  - CVE-2015-2152: XSA-119: HVM qemu was unexpectedly     enabling emulated VGA graphics backends.

  - CVE-2014-3615: Information leakage when guest sets high     graphics resolution.

  - CVE-2015-0361: XSA-116: A xen crash due to use after     free on hvm guest teardown.

  - CVE-2014-9065, CVE-2014-9066: XSA-114: xen: p2m lock     starvation.

Also the following bugs were fixed :

  - bnc#919098 - XEN blktap device intermittently fails to     connect

  - bnc#882089 - Windows 2012 R2 fails to boot up with     greater than 60 vcpus

  - bnc#903680 - Problems with detecting free loop devices     on Xen guest startup

  - bnc#861318 - xentop reports 'Found interface vif101.0     but domain 101 does not exist.'

  - Update seabios to rel-1.7.3.1 which is the correct     version for Xen 4.4

  - Enhancement to virsh/libvirtd 'send-key' command The xen     side small fix. (FATE#317240)

  - bnc#901488 - Intel ixgbe driver assigns rx/tx queues per     core resulting in irq problems on servers with a large     amount of CPU cores

  - bnc#910254 - SLES11 SP3 Xen VT-d igb NIC doesn't work

  - Add domain_migrate_constraints_set API to Xend's http     interface (FATE#317239)

  - Restore missing fixes from block-dmmd script

  - bnc#904255 - XEN boot hangs in early boot on UEFI system

  - bsc#912011 - high ping latency after upgrade to latest     SLES11SP3 on xen Dom0

  - Fix missing banner by restoring the figlet program.

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.

Xen was updated to 4.3.4 to fix multiple vulnerabities and non-security bugs.

The following vulnerabilities were fixed :

  - Long latency MMIO mapping operations are not preemptible     (XSA-125 CVE-2015-2752 bnc#922705)

  - Unmediated PCI command register access in qemu (XSA-126     CVE-2015-2756 bnc#922706)

  - Hypervisor memory corruption due to x86 emulator flaw     (bnc#919464 CVE-2015-2151 XSA-123)

  - Information leak through version information hypercall     (bnc#918998 CVE-2015-2045 XSA-122)

  - Information leak via internal x86 system device     emulation (bnc#918995 (CVE-2015-2044 XSA-121)

  - HVM qemu unexpectedly enabling emulated VGA graphics     backends (bnc#919663 CVE-2015-2152 XSA-119)

  - information leakage when guest sets high resolution     (bnc#895528 CVE-2014-3615)

The following non-security bugs were fixed :

  - L3: XEN blktap device intermittently fails to connect     (bnc#919098) 

  - Problems with detecting free loop devices on Xen guest     startup (bnc#903680)

  - xentop reports 'Found interface vif101.0 but domain 101     does not exist.' (bnc#861318) 

  - Intel ixgbe driver assigns rx/tx queues per core     resulting in irq problems on servers with a large amount     of CPU cores (bnc#901488)

  - SLES11 SP3 Xen VT-d igb NIC doesn't work (bnc#910254)

The remote host is affected by the vulnerability described in GLSA-201504-04 (Xen: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in Xen.  Please review the       CVE identifiers referenced below for details.
  Impact :

    A local attacker could possibly cause a Denial of Service condition or       obtain sensitive information.
  Workaround :

    There is no known workaround at this time.

Additional patch for XSA-98 on arm64 HVM qemu unexpectedly enabling emulated VGA graphics backends [XSA-119, CVE-2015-2152] Hypervisor memory corruption due to x86 emulator flaw [XSA-123, CVE-2015-2151] enable building pngs from fig files which is working again, fix oxenstored.service preset preuninstall script, arm: vgic: incorrect rate limiting of guest triggered logging, Information leak via internal x86 system device emulation, Information leak through version information hypercall

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

HVM qemu unexpectedly enabling emulated VGA graphics backends [XSA-119, CVE-2015-2152] Hypervisor memory corruption due to x86 emulator flaw [XSA-123, CVE-2015-2151] Information leak via internal x86 system device emulation, Information leak through version information hypercall

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

Additional patch for XSA-98 on arm64 HVM qemu unexpectedly enabling emulated VGA graphics backends [XSA-119, CVE-2015-2152] Hypervisor memory corruption due to x86 emulator flaw [XSA-123, CVE-2015-2151] Information leak via internal x86 system device emulation, Information leak through version information hypercall, fix a typo in xen.fedora.systemd.patch

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

ID	Name	Product	Family	Severity
140019	OracleVM 3.4 : xen (OVMSA-2020-0039) (Bunker Buster) (Foreshadow) (MDSUM/RIDL) (MFBDS/RIDL/ZombieLoad) (MLPDS/RIDL) (MSBDS/Fallout) (Meltdown) (POODLE) (Spectre)	Nessus	OracleVM Local Security Checks	critical
111992	OracleVM 3.4 : xen (OVMSA-2018-0248) (Bunker Buster) (Foreshadow) (Meltdown) (POODLE) (Spectre)	Nessus	OracleVM Local Security Checks	critical
85038	OracleVM 3.2 : xen (OVMSA-2015-0096)	Nessus	OracleVM Local Security Checks	high
85037	OracleVM 3.3 : xen (OVMSA-2015-0095)	Nessus	OracleVM Local Security Checks	high
84693	FreeBSD : xen-tools -- HVM qemu unexpectedly enabling emulated VGA graphics backends (0d732fd1-27e0-11e5-a4a5-002590263bf5)	Nessus	FreeBSD Local Security Checks	low
84333	openSUSE Security Update : xen (openSUSE-2015-434) (Venom)	Nessus	SuSE Local Security Checks	high
83707	SUSE SLED12 / SLES12 Security Update : Xen (SUSE-SU-2015:0613-1)	Nessus	SuSE Local Security Checks	high
82907	openSUSE Security Update : xen (openSUSE-2015-314)	Nessus	SuSE Local Security Checks	high
82734	GLSA-201504-04 : Xen: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	high
82054	Fedora 21 : xen-4.4.1-16.fc21 (2015-3944)	Nessus	Fedora Local Security Checks	high
82051	Fedora 20 : xen-4.3.3-12.fc20 (2015-3721)	Nessus	Fedora Local Security Checks	high
81987	Fedora 22 : xen-4.5.0-6.fc22 (2015-3935)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2015-2152

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Tenable Plugins

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