In FreeBSD 12.0-STABLE before r350619, 12.0-RELEASE before 12.0-RELEASE-p9, 11.3-STABLE before r350619, 11.3-RELEASE before 11.3-RELEASE-p2, and 11.2-RELEASE before 11.2-RELEASE-p13, the bhyve e1000 device emulation used a guest-provided value to determine the size of the on-stack buffer without validation when TCP segmentation offload is requested for a transmitted packet. A misbehaving bhyve guest could overwrite memory in the bhyve process on the host.

In FreeBSD 12.0-STABLE before r350222, 12.0-RELEASE before 12.0-RELEASE-p8, 11.3-STABLE before r350223, 11.3-RELEASE before 11.3-RELEASE-p1, and 11.2-RELEASE before 11.2-RELEASE-p12, rights transmitted over a domain socket did not properly release a reference on transmission error allowing a malicious user to cause the reference counter to wrap, forcing a free event. This could allow a malicious local user to gain root privileges or escape from a jail.

In FreeBSD 12.0-STABLE before r349805, 12.0-RELEASE before 12.0-RELEASE-p8, 11.3-STABLE before r349806, 11.3-RELEASE before 11.3-RELEASE-p1, and 11.2-RELEASE before 11.2-RELEASE-p12, code which handles close of a descriptor created by posix_openpt fails to undo a signal configuration. This causes an incorrect signal to be raised leading to a write after free of kernel memory allowing a malicious user to gain root privileges or escape a jail.

In FreeBSD 11.3-STABLE before r350217, 11.3-RELEASE before 11.3-RELEASE-p1, and 11.2-RELEASE before 11.2-RELEASE-p12, due to insufficient initialization of memory copied to userland in the freebsd32_ioctl interface, small amounts of kernel memory may be disclosed to userland processes. This may allow an attacker to leverage this information to obtain elevated privileges either directly or indirectly.

In FreeBSD 12.0-STABLE before r350261, 12.0-RELEASE before 12.0-RELEASE-p8, 11.3-STABLE before r350263, 11.3-RELEASE before 11.3-RELEASE-p1, and 11.2-RELEASE before 11.2-RELEASE-p12, system calls operating on file descriptors as part of mqueuefs did not properly release the reference allowing a malicious user to overflow the counter allowing access to files, directories, and sockets opened by processes owned by other users.

In FreeBSD 12.0-STABLE before r350246, 12.0-RELEASE before 12.0-RELEASE-p8, 11.3-STABLE before r350247, 11.3-RELEASE before 11.3-RELEASE-p1, and 11.2-RELEASE before 11.2-RELEASE-p12, the emulated XHCI device included with the bhyve hypervisor did not properly validate data provided by the guest, allowing an out-of-bounds read. This provides a malicious guest the possibility to crash the system or access system memory.

In FreeBSD 12.0-STABLE before r347474, 12.0-RELEASE before 12.0-RELEASE-p7, 11.2-STABLE before r347475, and 11.2-RELEASE before 11.2-RELEASE-p11, a bug in the FFS implementation causes up to three bytes of kernel stack memory to be written to disk as uninitialized directory entry padding.

In FreeBSD 12.0-STABLE before r349628, 12.0-RELEASE before 12.0-RELEASE-p7, 11.3-PRERELEASE before r349629, 11.3-RC3 before 11.3-RC3-p1, and 11.2-RELEASE before 11.2-RELEASE-p11, a bug in the cdrom driver allows users with read access to the cdrom device to arbitrarily overwrite kernel memory when media is present thereby allowing a malicious user in the operator group to gain root privileges.

In FreeBSD 12.0-STABLE before r349622, 12.0-RELEASE before 12.0-RELEASE-p7, 11.3-PRERELEASE before r349624, 11.3-RC3 before 11.3-RC3-p1, and 11.2-RELEASE before 11.2-RELEASE-p11, a bug in iconv implementation may allow an attacker to write past the end of an output buffer. Depending on the implementation, an attacker may be able to create a denial of service, provoke incorrect program behavior, or induce a remote code execution.

In FreeBSD 12.0-STABLE before r349197 and 12.0-RELEASE before 12.0-RELEASE-p6, a bug in the non-default RACK TCP stack can allow an attacker to cause several linked lists to grow unbounded and cause an expensive list traversal on every packet being processed, leading to resource exhaustion and a denial of service.