ASA-2019-00669 – OpenBSD: Dynamic Loader Privilege Escalation

OpenBSD  allows local users to escalate to root because a check for LD_LIBRARY_PATH in setuid programs can be defeated by setting a very small RLIMIT_DATA resource limit. When executing chpass or passwd (which are setuid root), _dl_setup_env in tries to strip LD_LIBRARY_PATH from the environment, but fails when it cannot allocate memory. Thus, the attacker is able to execute their own library code as root.

ASA-2019-00653 – OpenBSD: Local privilege escalation via S/Key and YubiKey

OpenBSD, in a non-default configuration where S/Key or YubiKey authentication is enabled, allows local users to become root by leveraging membership in the auth group. This occurs because root's file can be written to /etc/skey or /var/db/yubikey, and need not be owned by root.

ASA-2019-00650 – OpenBSD: Local privilege escalation via su

A local attacker can exploit su's -L option ("Loop until a correct username and password combination is entered") to log in as themselves but with another user's login class (with the exception of root's login class if the attacker is not in the group "wheel"), because the class variable is set once and never reset.

ASA-2019-00628 – Xen: Missing descriptor table limit checking in x86 PV emulation

When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don't install any LDT by default).

ASA-2019-00630 – Linux kernel: Wrong locking causes race conditions on streaming stop in vivid driver

An issue was discovered in drivers/media/platform/vivid in the Linux kernel. It is exploitable for privilege escalation on some Linux distributions where local users have /dev/video0 access, but only if the driver happens to be loaded. There are multiple race conditions during streaming stopping in this driver (part of the V4L2 subsystem).