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.

BZ2_decompress in decompress.c in bzip2 through 1.0.6 has an out-of-bounds write when there are many selectors.

In FreeBSD 11.3-PRERELEASE before r345378, 12.0-STABLE before r345377, 11.2-RELEASE before 11.2-RELEASE-p10, and 12.0-RELEASE before 12.0-RELEASE-p4, a bug in pf does not check if the outer ICMP or ICMP6 packet has the same destination IP as the source IP of the inner protocol packet allowing a maliciously crafted ICMP/ICMP6 packet could bypass the packet filter rules and be passed to a host that would otherwise be unavailable.