Kernel: error in exception handling leads to DoS

A statement in the System Programming Guide of the Intel 64 and IA-32 Architectures Software Developer's Manual (SDM) was mishandled in the development of some or all operating-system kernels, resulting in unexpected behavior for #DB exceptions that are deferred by MOV SS or POP SS, as demonstrated by (for example) privilege escalation in Windows, macOS, some Xen configurations, or FreeBSD, or a Linux kernel crash. The MOV to SS and POP SS instructions inhibit interrupts (including NMIs), data breakpoints, and single step trap exceptions until the instruction boundary following the next instruction (SDM Vol. 3A; section 6.8.3). (The inhibited data breakpoints are those on memory accessed by the MOV to SS or POP to SS instruction itself.) Note that debug exceptions are not inhibited by the interrupt enable (EFLAGS.IF) system flag (SDM Vol. 3A; section 2.3). If the instruction following the MOV to SS or POP to SS instruction is an instruction like SYSCALL, SYSENTER, INT 3, etc. that transfers control to the operating system at CPL < 3, the debug exception is delivered after the transfer to CPL < 3 is complete. OS kernels may not expect this order of events and may therefore experience unexpected behavior when it occurs.

Kernel: FPU state information leakage via lazy FPU restore

System software utilizing Lazy FP state restore technique on systems using Intel Core-based microprocessors may potentially allow a local process to infer data from another process through a speculative execution side channel.

xen: x86: DoS from attempting to use INVPCID with a non-canonical addresses

An issue was discovered in Xen through 4.11.x allowing 64-bit PV guest OS users to cause a denial of service (host OS crash) because #GP[0] can occur after a non-canonical address is passed to the TLB flushing code. NOTE: this issue exists because of an incorrect CVE-2017-5754 (aka Meltdown) mitigation.

xen: insufficient TLB flushing / improper large page mappings with AMD IOMMUs

An issue was discovered in Xen through 4.11.x on AMD x86 platforms, possibly allowing guest OS users to gain host OS privileges because small IOMMU mappings are unsafely combined into larger ones.

xen: insufficient TLB flushing / improper large page mappings with AMD IOMMUs

An issue was discovered in Xen through 4.11.x on AMD x86 platforms, possibly allowing guest OS users to gain host OS privileges because TLB flushes do not always occur after IOMMU mapping changes.

An Incorrect Access Control vulnerability has been identified in Citrix XenMobile Server 10.8.0 before Rolling Patch 6 and 10.9.0 before Rolling Patch 3. An attacker can impersonate and take actions on behalf of any Mobile Application Management (MAM) enrolled device.

* Lack of authentication in Citrix Xen Mobile through 10.8 allows low-privileged local users to execute system commands as root by making requests to private services listening on ports 8000, 30000 and 30001. NOTE: the vendor disputes that this is a vulnerability, stating it is "already mitigated by the internal firewall that limits access to configuration services to localhost.

* Xen Mobile through 10.8.0 includes a service listening on port 5001 within its firewall that accepts unauthenticated input. If this service is supplied with raw serialised Java objects, it deserialises them back into Java objects in memory, giving rise to a remote code execution vulnerability. NOTE: the vendor disputes that this is a vulnerability, stating it is "already mitigated by the internal firewall that limits access to configuration services to localhost.

Citrix XenServer 7.1 and newer allows Directory Traversal.

iSM: Dell EMC iDRAC Service Module Improper File Permission Vulnerability

Dell EMC iDRAC Service Module for all supported Linux and XenServer versions v3.0.1, v3.0.2, v3.1.0, v3.2.0, when started, changes the default file permission of the hosts file of the host operating system (/etc/hosts) to world writable. A malicious low privileged operating system user or process could modify the host file and potentially redirect traffic from the intended destination to sites hosting malicious or unwanted content.

There is a Hazelcast Library Java Deserialization Vulnerability in Citrix XenMobile Server 10.8 before RP2 and 10.7 before RP3.

There is an XML External Entity (XXE) Processing Vulnerability in Citrix XenMobile Server 10.8 before RP2 and 10.7 before RP3.

There is a Sensitive Data Leakage issue in Citrix XenMobile Server 10.7 before RP3.

There are Open Redirect Vulnerabilities in Citrix XenMobile Server 10.8 before RP2 and 10.7 before RP3.

There is an Insufficient Path Validation Vulnerability in Citrix XenMobile Server 10.8 before RP2 and 10.7 before RP3.

There is a Cross-Site Scripting Vulnerability in Citrix XenMobile Server 10.7 before RP3.

There are Unauthenticated File Upload Vulnerabilities in Citrix XenMobile Server 10.8 before RP2 and 10.7 before RP3.

Qemu: display: cirrus: potential arbitrary code execution via cirrus_bitblt_cputovideo

Quick emulator (QEMU) before 2.8 built with the Cirrus CLGD 54xx VGA Emulator support is vulnerable to an out-of-bounds access issue. The issue could occur while copying VGA data in cirrus_bitblt_cputovideo. A privileged user inside guest could use this flaw to crash the QEMU process OR potentially execute arbitrary code on host with privileges of the QEMU process.

Qemu: display: cirrus: oob access while doing bitblt copy backward mode

Quick emulator (QEMU) built with the Cirrus CLGD 54xx VGA emulator support is vulnerable to an out-of-bounds access issue. It could occur while copying VGA data via bitblt copy in backward mode. A privileged user inside a guest could use this flaw to crash the QEMU process resulting in DoS or potentially execute arbitrary code on the host with privileges of QEMU process on the host.

Qemu: cirrus: heap buffer overflow via vnc connection

A heap buffer overflow flaw was found in QEMU's Cirrus CLGD 54xx VGA emulator's VNC display driver support before 2.9; the issue could occur when a VNC client attempted to update its display after a VGA operation is performed by a guest. A privileged user/process inside a guest could use this flaw to crash the QEMU process or, potentially, execute arbitrary code on the host with privileges of the QEMU process.