xen : various security flaws (#1397383) x86 null segments not always treated as unusable [XSA-191, CVE-2016-9386] x86 task switch to VM86 mode mis-handled [XSA-192, CVE-2016-9382] x86 segment base write emulation lacking canonical address checks [XSA-193, CVE-2016-9385] x86 64-bit bit test instruction emulation broken [XSA-195, CVE-2016-9383] x86 software interrupt injection mis-handled [XSA-196, CVE-2016-9377, CVE-2016-9378] qemu incautious about shared ring processing [XSA-197, CVE-2016-9381] delimiter injection vulnerabilities in pygrub [XSA-198, CVE-2016-9379, CVE-2016-9380]

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

xen was updated to version 4.7.1 to fix 17 security issues.

These security issues were fixed :

  - CVE-2016-9637: ioport array overflow allowing a     malicious guest administrator can escalate their     privilege to that of the host (bsc#1011652).

  - CVE-2016-9386: x86 null segments were not always treated     as unusable allowing an unprivileged guest user program     to elevate its privilege to that of the guest operating     system. Exploit of this vulnerability is easy on Intel     and more complicated on AMD (bsc#1009100).

  - CVE-2016-9382: x86 task switch to VM86 mode was     mis-handled, allowing a unprivileged guest process to     escalate its privilege to that of the guest operating     system on AMD hardware. On Intel hardware a malicious     unprivileged guest process can crash the guest     (bsc#1009103).

  - CVE-2016-9385: x86 segment base write emulation lacked     canonical address checks, allowing a malicious guest     administrator to crash the host (bsc#1009104).

  - CVE-2016-9384: Guest 32-bit ELF symbol table load     leaking host data to unprivileged guest users     (bsc#1009105).

  - CVE-2016-9383: The x86 64-bit bit test instruction     emulation was broken, allowing a guest to modify     arbitrary memory leading to arbitray code execution     (bsc#1009107).

  - CVE-2016-9377: x86 software interrupt injection was     mis-handled, allowing an unprivileged guest user to     crash the guest (bsc#1009108).

  - CVE-2016-9378: x86 software interrupt injection was     mis-handled, allowing an unprivileged guest user to     crash the guest (bsc#1009108)

  - CVE-2016-9381: Improper processing of shared rings     allowing guest administrators take over the qemu     process, elevating their privilege to that of the qemu     process (bsc#1009109).

  - CVE-2016-9379: Delimiter injection vulnerabilities in     pygrub allowed guest administrators to obtain the     contents of sensitive host files or delete the files     (bsc#1009111).

  - CVE-2016-9380: Delimiter injection vulnerabilities in     pygrub allowed guest administrators to obtain the     contents of sensitive host files or delete the files     (bsc#1009111).

  - CVE-2016-7777: Xen did not properly honor CR0.TS and     CR0.EM, which allowed local x86 HVM guest OS users to     read or modify FPU, MMX, or XMM register state     information belonging to arbitrary tasks on the guest by     modifying an instruction while the hypervisor is     preparing to emulate it (bsc#1000106).

  - CVE-2016-8910: The rtl8139_cplus_transmit function in     hw/net/rtl8139.c allowed local guest OS administrators     to cause a denial of service (infinite loop and CPU     consumption) by leveraging failure to limit the ring     descriptor count (bsc#1007157).

  - CVE-2016-8667: The rc4030_write function in     hw/dma/rc4030.c in allowed local guest OS administrators     to cause a denial of service (divide-by-zero error and     QEMU process crash) via a large interval timer reload     value (bsc#1005004).

  - CVE-2016-8669: The serial_update_parameters function in     hw/char/serial.c allowed local guest OS administrators     to cause a denial of service (divide-by-zero error and     QEMU process crash) via vectors involving a value of     divider greater than baud base (bsc#1005005).

  - CVE-2016-7908: The mcf_fec_do_tx function in     hw/net/mcf_fec.c did not properly limit the buffer     descriptor count when transmitting packets, which     allowed local guest OS administrators to cause a denial     of service (infinite loop and QEMU process crash) via     vectors involving a buffer descriptor with a length of 0     and crafted values in bd.flags (bsc#1003030).

  - CVE-2016-7909: The pcnet_rdra_addr function in     hw/net/pcnet.c allowed local guest OS administrators to     cause a denial of service (infinite loop and QEMU     process crash) by setting the (1) receive or (2)     transmit descriptor ring length to 0 (bsc#1003032).

These non-security issues were fixed :

  - bsc#1004981: Xen RPM didn't contain debug hypervisor for     EFI systems

  - bsc#1007941: Xen tools limited the number of vcpus to     256 

This update was imported from the SUSE:SLE-12-SP2:Update update project.

According to its self-reported version number, the Xen hypervisor installed on the remote host is missing a security update. It is, therefore, affected by multiple vulnerabilities :

  - A flaw exists in the inject_swint() function in     x86_emulate.c due to improper handling of the format of     IDT lookups when emulating instructions which generate     software interrupts. A guest attacker can exploit this     to crash the host, resulting in a denial of service     condition. (CVE-2016-9377)

  - A flaw exists in the svm_inject_trap() function in svm.c     due to a failure to properly perform IDT privilege     checks when emulating instructions which generate     software interrupts. A guest attacker can exploit this     to crash the host, resulting in a denial of service     condition. (CVE-2016-9378)

  - A flaw exists in the sniff_netware() function in file     tools/pygrub/src/pygrub due to improper handling of     string quotes and S-expressions in the bootloader when     the S-expressions output format is requested. A guest     attacker can exploit this to cause the bootloader     configuration file to produce incorrect output,     resulting in the disclosure or deletion of files from     the host. (CVE-2016-9379)

  - A flaw exists in the sniff_netware() function in file     tools/pygrub/src/pygrub due to improper handling of NULL     bytes in the bootloader when the null-delimited output     format is requested. A guest attacker can exploit this     to cause configuration files to output ambiguous or     confusing results, resulting in the disclosure or     deletion of files from the host. (CVE-2016-9380)

  - A double-fetch flaw exists that is triggered when the     compiler omits QEMU optimizations. A guest attacker can     exploit this to gain elevated privileges on the host.
    (CVE-2016-9381)

  - A flaw exists in the hvm_task_switch() function in hvm.c     due to improper handling of x86 task switching to VM86     mode. A guest attacker can exploit this to cause a     denial of service condition or gain elevated privileges     within the guest environment. (CVE-2016-9382)

  - A flaw exists in the x86_emulate() function in     x86_emulate.c that allows a guest attacker to cause     changes to memory and thereby gain elevated privileges     on the host. (CVE-2016-9383)

  - A flaw exists that is triggered as unused bytes in     image metadata are not properly cleared during symbol     table loading. This may allow a guest attacker to     disclose potentially sensitive information from the     host. (CVE-2016-9384)

  - A flaw exists due to improper clearing of unused bytes     in image metadata during symbol table loading. A guest     attacker can exploit this to disclose sensitive     information from the host. (CVE-2016-9384)

  - A flaw exists in the x86 segment base write emulation     due to a lack of canonical address checks. A guest     attacker can exploit this issue to crash the host,     resulting in a denial of service condition.
    (CVE-2016-9385)

  - A flaw exists in the x86 emulator due to improper     validation of the usability of segments when performing     memory accesses. A guest attacker can exploit this to     gain elevated privileges within the guest environment.
    (CVE-2016-9386)

Note that Nessus has checked the changeset versions based on the xen.git change log. Nessus did not check guest hardware configurations or if patches were applied manually to the source code before a recompile and reinstall.

xen was updated to version 4.7.1 to fix 17 security issues. These security issues were fixed :

  - CVE-2016-9637: ioport array overflow allowing a     malicious guest administrator can escalate their     privilege to that of the host (bsc#1011652).

  - CVE-2016-9386: x86 null segments were not always treated     as unusable allowing an unprivileged guest user program     to elevate its privilege to that of the guest operating     system. Exploit of this vulnerability is easy on Intel     and more complicated on AMD (bsc#1009100).

  - CVE-2016-9382: x86 task switch to VM86 mode was     mis-handled, allowing a unprivileged guest process to     escalate its privilege to that of the guest operating     system on AMD hardware. On Intel hardware a malicious     unprivileged guest process can crash the guest     (bsc#1009103).

  - CVE-2016-9385: x86 segment base write emulation lacked     canonical address checks, allowing a malicious guest     administrator to crash the host (bsc#1009104).

  - CVE-2016-9384: Guest 32-bit ELF symbol table load     leaking host data to unprivileged guest users     (bsc#1009105).

  - CVE-2016-9383: The x86 64-bit bit test instruction     emulation was broken, allowing a guest to modify     arbitrary memory leading to arbitray code execution     (bsc#1009107).

  - CVE-2016-9377: x86 software interrupt injection was     mis-handled, allowing an unprivileged guest user to     crash the guest (bsc#1009108).

  - CVE-2016-9378: x86 software interrupt injection was     mis-handled, allowing an unprivileged guest user to     crash the guest (bsc#1009108)

  - CVE-2016-9381: Improper processing of shared rings     allowing guest administrators take over the qemu     process, elevating their privilege to that of the qemu     process (bsc#1009109).

  - CVE-2016-9379: Delimiter injection vulnerabilities in     pygrub allowed guest administrators to obtain the     contents of sensitive host files or delete the files     (bsc#1009111).

  - CVE-2016-9380: Delimiter injection vulnerabilities in     pygrub allowed guest administrators to obtain the     contents of sensitive host files or delete the files     (bsc#1009111).

  - CVE-2016-7777: Xen did not properly honor CR0.TS and     CR0.EM, which allowed local x86 HVM guest OS users to     read or modify FPU, MMX, or XMM register state     information belonging to arbitrary tasks on the guest by     modifying an instruction while the hypervisor is     preparing to emulate it (bsc#1000106).

  - CVE-2016-8910: The rtl8139_cplus_transmit function in     hw/net/rtl8139.c allowed local guest OS administrators     to cause a denial of service (infinite loop and CPU     consumption) by leveraging failure to limit the ring     descriptor count (bsc#1007157).

  - CVE-2016-8667: The rc4030_write function in     hw/dma/rc4030.c in allowed local guest OS administrators     to cause a denial of service (divide-by-zero error and     QEMU process crash) via a large interval timer reload     value (bsc#1005004).

  - CVE-2016-8669: The serial_update_parameters function in     hw/char/serial.c allowed local guest OS administrators     to cause a denial of service (divide-by-zero error and     QEMU process crash) via vectors involving a value of     divider greater than baud base (bsc#1005005).

  - CVE-2016-7908: The mcf_fec_do_tx function in     hw/net/mcf_fec.c did not properly limit the buffer     descriptor count when transmitting packets, which     allowed local guest OS administrators to cause a denial     of service (infinite loop and QEMU process crash) via     vectors involving a buffer descriptor with a length of 0     and crafted values in bd.flags (bsc#1003030).

  - CVE-2016-7909: The pcnet_rdra_addr function in     hw/net/pcnet.c allowed local guest OS administrators to     cause a denial of service (infinite loop and QEMU     process crash) by setting the (1) receive or (2)     transmit descriptor ring length to 0 (bsc#1003032).

The update package also includes non-security fixes. See advisory for details.

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.

The remote host is affected by the vulnerability described in GLSA-201612-56 (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 execute arbitrary code with the       privileges of the process, could gain privileges on the host system,       cause a Denial of Service condition, or obtain sensitive information.
  Workaround :

    There is no known workaround at this time.

xen : various security flaws (#1397383) x86 null segments not always treated as unusable [XSA-191, CVE-2016-9386] x86 task switch to VM86 mode mis-handled [XSA-192, CVE-2016-9382] x86 segment base write emulation lacking canonical address checks [XSA-193, CVE-2016-9385] guest 32-bit ELF symbol table load leaking host data [XSA-194, CVE-2016-9384] x86 64-bit bit test instruction emulation broken [XSA-195, CVE-2016-9383] x86 software interrupt injection mis-handled [XSA-196, CVE-2016-9377, CVE-2016-9378] qemu incautious about shared ring processing [XSA-197, CVE-2016-9381] delimiter injection vulnerabilities in pygrub [XSA-198, CVE-2016-9379, CVE-2016-9380]

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

This update for xen to version 4.5.5 fixes several issues. These security issues were fixed :

  - CVE-2016-9637: ioport array overflow allowing a     malicious guest administrator can escalate their     privilege to that of the host (bsc#1011652)

  - CVE-2016-9386: x86 null segments were not always treated     as unusable allowing an unprivileged guest user program     to elevate its privilege to that of the guest operating     system. Exploit of this vulnerability is easy on Intel     and more complicated on AMD (bsc#1009100)

  - CVE-2016-9382: x86 task switch to VM86 mode was     mis-handled, allowing a unprivileged guest process to     escalate its privilege to that of the guest operating     system on AMD hardware. On Intel hardware a malicious     unprivileged guest process can crash the guest     (bsc#1009103)

  - CVE-2016-9385: x86 segment base write emulation lacked     canonical address checks, allowing a malicious guest     administrator to crash the host (bsc#1009104)

  - CVE-2016-9383: The x86 64-bit bit test instruction     emulation was broken, allowing a guest to modify     arbitrary memory leading to arbitray code execution     (bsc#1009107)

  - CVE-2016-9378: x86 software interrupt injection was     mis-handled, allowing an unprivileged guest user to     crash the guest (bsc#1009108)

  - CVE-2016-9377: x86 software interrupt injection was     mis-handled, allowing an unprivileged guest user to     crash the guest (bsc#1009108)

  - CVE-2016-9381: Improper processing of shared rings     allowing guest administrators take over the qemu     process, elevating their privilege to that of the qemu     process (bsc#1009109)

  - CVE-2016-9380: Delimiter injection vulnerabilities in     pygrub allowed guest administrators to obtain the     contents of sensitive host files or delete the files     (bsc#1009111)

  - CVE-2016-9379: Delimiter injection vulnerabilities in     pygrub allowed guest administrators to obtain the     contents of sensitive host files or delete the files     (bsc#1009111)

  - CVE-2016-7777: Xen did not properly honor CR0.TS and     CR0.EM, which allowed local x86 HVM guest OS users to     read or modify FPU, MMX, or XMM register state     information belonging to arbitrary tasks on the guest by     modifying an instruction while the hypervisor is     preparing to emulate it (bsc#1000106)

  - CVE-2016-8910: The rtl8139_cplus_transmit function in     hw/net/rtl8139.c allowed local guest OS administrators     to cause a denial of service (infinite loop and CPU     consumption) by leveraging failure to limit the ring     descriptor count (bsc#1007157)

  - CVE-2016-8909: The intel_hda_xfer function in     hw/audio/intel-hda.c allowed local guest OS     administrators to cause a denial of service (infinite     loop and CPU consumption) via an entry with the same     value for buffer length and pointer position     (bsc#1007160).

  - CVE-2016-8667: The rc4030_write function in     hw/dma/rc4030.c in allowed local guest OS administrators     to cause a denial of service (divide-by-zero error and     QEMU process crash) via a large interval timer reload     value (bsc#1005004)

  - CVE-2016-8669: The serial_update_parameters function in     hw/char/serial.c allowed local guest OS administrators     to cause a denial of service (divide-by-zero error and     QEMU process crash) via vectors involving a value of     divider greater than baud base (bsc#1005005)

  - CVE-2016-7995: A memory leak in ehci_process_itd allowed     a privileged user inside guest to DoS the host     (bsc#1003870).

  - CVE-2016-8576: The xhci_ring_fetch function in     hw/usb/hcd-xhci.c allowed local guest OS administrators     to cause a denial of service (infinite loop and QEMU     process crash) by leveraging failure to limit the number     of link Transfer Request Blocks (TRB) to process     (bsc#1004016).

  - CVE-2016-7908: The mcf_fec_do_tx function in     hw/net/mcf_fec.c did not properly limit the buffer     descriptor count when transmitting packets, which     allowed local guest OS administrators to cause a denial     of service (infinite loop and QEMU process crash) via     vectors involving a buffer descriptor with a length of 0     and crafted values in bd.flags (bsc#1003030)

  - CVE-2016-7909: The pcnet_rdra_addr function in     hw/net/pcnet.c allowed local guest OS administrators to     cause a denial of service (infinite loop and QEMU     process crash) by setting the (1) receive or (2)     transmit descriptor ring length to 0 (bsc#1003032)

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.

This updates xen to version 4.5.5 to fix the following issues :

  - An unprivileged user in a guest could gain guest could     escalate privilege to that of the guest kernel, if it     had could invoke the instruction emulator. Only 64-bit     x86 HVM guest were affected. Linux guest have not been     vulnerable. (boo#1016340, CVE-2016-10013)

  - An unprivileged user in a 64 bit x86 guest could gain     information from the host, crash the host or gain     privilege of the host (boo#1009107, CVE-2016-9383)

  - An unprivileged guest process could (unintentionally or     maliciously) obtain or ocorrupt sensitive information of     other programs in the same guest. Only x86 HVM guests     have been affected. The attacker needs to be able to     trigger the Xen instruction emulator. (boo#1000106,     CVE-2016-7777)

  - A guest on x86 systems could read small parts of     hypervisor stack data (boo#1012651, CVE-2016-9932)

  - A malicious guest kernel could hang or crash the host     system (boo#1014298, CVE-2016-10024)

  - The epro100 emulated network device caused a memory leak     in the host when unplugged in the guest. A privileged     user in the guest could use this to cause a DoS on the     host or potentially crash the guest process on the host     (boo#1013668, CVE-2016-9101)

  - The ColdFire Fast Ethernet Controller was vulnerable to     an infinite loop that could be trigged by a privileged     user in the guest, leading to DoS (boo#1013657,     CVE-2016-9776)

  - A malicious guest administrator could escalate their     privilege to that of the host. Only affects x86 HVM     guests using qemu older version 1.6.0 or using the     qemu-xen-traditional. (boo#1011652, CVE-2016-9637)

  - An unprivileged guest user could escalate privilege to     that of the guest administrator on x86 HVM guests,     especially on Intel CPUs (boo#1009100, CVE-2016-9386)

  - An unprivileged guest user could escalate privilege to     that of the guest administrator (on AMD CPUs) or crash     the system (on Intel CPUs) on 32-bit x86 HVM guests.
    Only guest operating systems that allowed a new task to     start in VM86 mode were affected. (boo#1009103,     CVE-2016-9382)

  - A malicious guest administrator could crash the host on     x86 PV guests only (boo#1009104, CVE-2016-9385)

  - An unprivileged guest user was able to crash the guest.
    (boo#1009108, CVE-2016-9377, CVE-2016-9378)

  - A malicious guest administrator could get privilege of     the host emulator process on x86 HVM guests.
    (boo#1009109, CVE-2016-9381)

  - A vulnerability in pygrub allowed a malicious guest     administrator to obtain the contents of sensitive host     files, or even delete those files (boo#1009111,     CVE-2016-9379, CVE-2016-9380)

  - A privileged guest user could cause an infinite loop in     the RTL8139 ethernet emulation to consume CPU cycles on     the host, causing a DoS situation (boo#1007157,     CVE-2016-8910)

  - A privileged guest user could cause an infinite loop in     the intel-hda sound emulation to consume CPU cycles on     the host, causing a DoS situation (boo#1007160,     CVE-2016-8909)

  - A privileged guest user could cause a crash of the     emulator process on the host by exploiting a divide by     zero vulnerability of the JAZZ RC4030 chipset emulation     (boo#1005004 CVE-2016-8667)

  - A privileged guest user could cause a crash of the     emulator process on the host by exploiting a divide by     zero issue of the 16550A UART emulation (boo#1005005,     CVE-2016-8669)

  - A privileged guest user could cause a memory leak in the     USB EHCI emulation, causing a DoS situation on the host     (boo#1003870, CVE-2016-7995)

  - A privileged guest user could cause an infinite loop in     the USB xHCI emulation, causing a DoS situation on the     host (boo#1004016, CVE-2016-8576)

  - A privileged guest user could cause an infinite loop in     the ColdFire Fash Ethernet Controller emulation, causing     a DoS situation on the host (boo#1003030, CVE-2016-7908)

  - A privileged guest user could cause an infinite loop in     the AMD PC-Net II emulation, causing a DoS situation on     the host (boo#1003032, CVE-2016-7909)

  - Cause a reload of clvm in the block-dmmd script to avoid     a blocking lvchange call (boo#1002496)

ID	Name	Product	Family	Published	Updated	Severity
95491	Fedora 23 : xen (2016-68b71978a1)	Nessus	Fedora Local Security Checks	12/5/2016	1/11/2021	high
95910	openSUSE Security Update : xen (openSUSE-2016-1477)	Nessus	SuSE Local Security Checks	12/16/2016	1/19/2021	high
95630	Xen Multiple Vulnerabilities (XSA-191 - XSA-198)	Nessus	Misc.	12/8/2016	7/10/2020	high
95709	SUSE SLED12 / SLES12 Security Update : xen (SUSE-SU-2016:3067-1)	Nessus	SuSE Local Security Checks	12/12/2016	1/6/2021	high
95492	Fedora 24 : xen (2016-95c104a4c6)	Nessus	Fedora Local Security Checks	12/5/2016	1/11/2021	high
96231	GLSA-201612-56 : Xen: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	1/3/2017	1/11/2021	high
95493	Fedora 25 : xen (2016-999e1a6927)	Nessus	Fedora Local Security Checks	12/5/2016	1/11/2021	high
95761	SUSE SLED12 / SLES12 Security Update : xen (SUSE-SU-2016:3083-1)	Nessus	SuSE Local Security Checks	12/13/2016	1/6/2021	high
96252	openSUSE Security Update : xen (openSUSE-2017-4)	Nessus	SuSE Local Security Checks	1/3/2017	1/19/2021	high

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