In dnsmasq before 2.78, if the DNS packet size does not match the expected size, the size parameter in a memset call gets a negative value. As it is an unsigned value, memset ends up writing up to 0xffffffff zero's (0xffffffffffffffff in 64 bit platforms), making dnsmasq crash.
The specific flaw exists within the crUnpackTexGendv method. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length buffer. An attacker can leverage this vulnerability to crash the VirtualBox process used for open the target.
The amd64_set_ldt() function in sys/amd64/amd64/sys_machdep.c in the FreeBSD kernel code is prone to an integer signedness error when processing a system call with specially crafted parameters originated from user space.

This issue ultimately leads to a kernel heap overflow, which can be used by unprivileged local attackers to cause a kernel panic and crash the machine.