The ntpd client in NTP 4.x before 4.2.8p4 and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service via a number of crafted "KOD" messages.
A flaw was found in the way NTP handled rate limiting. An attacker able to send a large number of crafted requests to an NTP server could trigger the rate limiting on that server, and prevent clients from getting a usable reply from the server.
The default NTP configuration in Red Hat Enterprise Linux does not enable rate limiting.
External References:
https://www.cs.bu.edu/~goldbe/NTPattack.html
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.
The PV pagetable code in arch/x86/mm.c in Xen 4.7.x and earlier allows local 32-bit PV guest OS administrators to gain host OS privileges by leveraging fast-paths for updating pagetable entries.
Xen 4.5.x through 4.7.x do not implement Supervisor Mode Access Prevention (SMAP) whitelisting in 32-bit exception and event delivery, which allows local 32-bit PV guest OS kernels to cause a denial of service (hypervisor and VM crash) by triggering a safety check.
Citrix XenServer 7.0 before Hotfix XS70E003, when a deployment has been upgraded from an earlier release, might allow remote attackers on the management network to "compromise" a host by leveraging credentials for an Active Directory account.
Qemu emulator built with VGA emulation with VESA BIOS Extensions(VBE) support is vulnerable to an OOB r/w access issue. It could occur while doing VGA r/w operations via i/o port methods.
A privileged guest user could use this flaw to potentially execute arbitrary code, with privileges of the Qemu process on the host.
Upstream patch: --------------- -> https://lists.gnu.org/archive/html/qemu-devel/2016-05/msg01197.html
Reference: ---------- -> http://www.openwall.com/lists/oss-security/2016/05/09/3
Integer overflow in the VGA module in QEMU allows local guest OS users to cause a denial of service (out-of-bounds read and QEMU process crash) by editing VGA registers in VBE mode.
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 cirrusbitbltcputovideo. 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.
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.
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.
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 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.