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    CVE-2016-4020

    The patch_instruction function in hw/i386/kvmvapic.c in QEMU does not initialize the imm32 variable, which allows local guest OS administrators to obtain sensitive information from host stack memory by accessing the Task Priority Register (TPR).

    Published:Apr 7, 2016
    Last Modified:Apr 12, 2025
    EPS:May 25, 2016
    EPSS Score:0.00064
    CVSS Score:6.5

    Affected Products

    Vendor
    Canonical
    Product
    Ubuntu Linux
    Vendor
    Debian
    Product
    Debian Linux
    Vendor
    Qemu
    Product
    Qemu
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    Redhat
    Product
    Enterprise Linux Desktop
    Vendor
    Redhat
    Product
    Enterprise Linux Eus
    Vendor
    Redhat
    Product
    Enterprise Linux Server
    Vendor
    Redhat
    Product
    Enterprise Linux Server Aus
    Vendor
    Redhat
    Product
    Enterprise Linux Server Tus
    Vendor
    Redhat
    Product
    Enterprise Linux Workstation
    Vendor
    Redhat
    Product
    Openstack
    Vendor
    Redhat
    Product
    Virtualization

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-116 Excavation
    CAPEC-13 Subverting Environment Variable Values
    CAPEC-169 Footprinting
    CAPEC-22 Exploiting Trust in Client
    CAPEC-224 Fingerprinting
    CAPEC-285 ICMP Echo Request Ping
    CAPEC-287 TCP SYN Scan
    CAPEC-290 Enumerate Mail Exchange (MX) Records
    CAPEC-291 DNS Zone Transfers
    CAPEC-292 Host Discovery
    CAPEC-293 Traceroute Route Enumeration
    CAPEC-294 ICMP Address Mask Request
    CAPEC-295 Timestamp Request
    CAPEC-296 ICMP Information Request
    CAPEC-297 TCP ACK Ping
    CAPEC-298 UDP Ping
    CAPEC-299 TCP SYN Ping
    CAPEC-300 Port Scanning
    CAPEC-301 TCP Connect Scan
    CAPEC-302 TCP FIN Scan
    CAPEC-303 TCP Xmas Scan
    CAPEC-304 TCP Null Scan
    CAPEC-305 TCP ACK Scan
    CAPEC-306 TCP Window Scan
    CAPEC-307 TCP RPC Scan
    CAPEC-308 UDP Scan
    CAPEC-309 Network Topology Mapping
    CAPEC-310 Scanning for Vulnerable Software
    CAPEC-312 Active OS Fingerprinting
    CAPEC-313 Passive OS Fingerprinting
    CAPEC-317 IP ID Sequencing Probe
    CAPEC-318 IP 'ID' Echoed Byte-Order Probe
    CAPEC-319 IP (DF) 'Don't Fragment Bit' Echoing Probe
    CAPEC-320 TCP Timestamp Probe
    CAPEC-321 TCP Sequence Number Probe
    CAPEC-322 TCP (ISN) Greatest Common Divisor Probe
    CAPEC-323 TCP (ISN) Counter Rate Probe
    CAPEC-324 TCP (ISN) Sequence Predictability Probe
    CAPEC-325 TCP Congestion Control Flag (ECN) Probe
    CAPEC-326 TCP Initial Window Size Probe
    CAPEC-327 TCP Options Probe
    CAPEC-328 TCP 'RST' Flag Checksum Probe
    CAPEC-329 ICMP Error Message Quoting Probe
    CAPEC-330 ICMP Error Message Echoing Integrity Probe
    CAPEC-472 Browser Fingerprinting
    CAPEC-497 File Discovery
    CAPEC-508 Shoulder Surfing
    CAPEC-573 Process Footprinting
    CAPEC-574 Services Footprinting
    CAPEC-575 Account Footprinting
    CAPEC-576 Group Permission Footprinting
    CAPEC-577 Owner Footprinting
    CAPEC-59 Session Credential Falsification through Prediction
    CAPEC-60 Reusing Session IDs (aka Session Replay)
    CAPEC-616 Establish Rogue Location
    CAPEC-643 Identify Shared Files/Directories on System
    CAPEC-646 Peripheral Footprinting
    CAPEC-651 Eavesdropping
    CAPEC-79 Using Slashes in Alternate Encoding

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    CVE-2026-47336 (CVSS 3.3) — Ubuntu Linux 6.8 contains SAUCE patches with a possible use of an uninitialized variable in AppArmor AF_INET/A…
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    CVE-2026-47333 (CVSS 7.8) — Ubuntu Linux 6.8, 6.17 and 7.0 contain AppArmor SAUCE patches which can potentially incorrectly compute the si…
    CVE-2026-47332 (CVSS 5.5) — Ubuntu Linux 6.8, 6.17 and 7.0 contain AppArmor SAUCE patches which incorrectly validate the size of an intern…
    CVE-2026-47331 (CVSS 7.8) — Ubuntu Linux 6.8 contains AppArmor SAUCE patches which fail to acquire a lock when modifying a linked list. An…
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    References

    http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=691a02e2ce0c413236a78dee6f2651c937b09fb0
    http://www.securityfocus.com/bid/86067
    http://www.ubuntu.com/usn/USN-2974-1
    https://access.redhat.com/errata/RHSA-2017:1856
    https://access.redhat.com/errata/RHSA-2017:2392
    https://access.redhat.com/errata/RHSA-2017:2408
    https://bugzilla.redhat.com/show_bug.cgi?id=1313686
    https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html
    https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.html
    https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.html
    https://security.gentoo.org/glsa/201609-01
    http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=691a02e2ce0c413236a78dee6f2651c937b09fb0
    http://www.securityfocus.com/bid/86067
    http://www.ubuntu.com/usn/USN-2974-1
    https://access.redhat.com/errata/RHSA-2017:1856
    https://access.redhat.com/errata/RHSA-2017:2392
    https://access.redhat.com/errata/RHSA-2017:2408
    https://bugzilla.redhat.com/show_bug.cgi?id=1313686
    https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html
    https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.html
    https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.html
    https://security.gentoo.org/glsa/201609-01

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High