A vulnerability was discovered in Linux, FreeBSD, OpenBSD, MacOS, iOS, and Android that allows a malicious access point, or an adjacent user, to determine if a connected user is using a VPN, make positive inferences about the websites they are visiting, and determine the correct sequence and acknowledgement numbers in use, allowing the bad actor to inject data into the TCP stream. This provides everything that is needed for an attacker to hijack active connections inside the VPN tunnel.

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 before 11.1-STABLE, 11.2-RELEASE-p2, 11.1-RELEASE-p13, ip fragment reassembly code is vulnerable to a denial of service due to excessive system resource consumption. This issue can allow a remote attacker who is able to send an arbitrary ip fragments to cause the machine to consume excessive resources.

Improper bounds checking of the obuf variable in the link_ntoa() function in linkaddr.c of the BSD libc library may allow an attacker to read or write from memory. The full impact and severity depends on the method of exploit and how the library is used by applications. According to analysis by FreeBSD developers, it is very unlikely that applications exist that utilize link_ntoa() in an exploitable manner, and the CERT/CC is not aware of any proof of concept. A blog post describes the functionality of link_ntoa() and points out that none of the base utilities use this function in an exploitable manner. For more information, please see FreeBSD Security Advisory SA-16:37.

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.

An exploitable denial of service vulnerability exists in the origin timestamp check functionality of ntpd 4.2.8p9. A specially crafted unauthenticated network packet can be used to reset the expected origin timestamp for target peers. Legitimate replies from targeted peers will fail the origin timestamp check (TEST2) causing the reply to be dropped and creating a denial of service condition.