fpregs_state_valid in arch/x86/include/asm/fpu/internal.h in the Linux kernel, when GCC 9 is used, allows context-dependent attackers to cause a denial of service (memory corruption) or possibly have unspecified other impact because of incorrect fpu_fpregs_owner_ctx caching, as demonstrated by mishandling of signal-based non-cooperative preemption in Go 1.14 prereleases on amd64.
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 ld.so 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.
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.
libc in OpenBSD allows authentication bypass via the -schallenge username, as demonstrated by smtpd, ldapd, or radiusd. This is related to gen/auth_subr.c and gen/authenticate.c in libc (and login/login.c and xenocara/app/xenodm/greeter/verify.c).
xlock in OpenBSD allows local users to gain the privileges of the auth group by providing a LIBGL_DRIVERS_PATH environment variable, because xenocara/lib/mesa/src/loader/loader.c mishandles dlopen.
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.
Recursive clones are currently affected by a vulnerability that is caused by too-lax validation of submodule names, allowing very targeted attacks via remote code execution in recursive clones.
Filenames on Linux/Unix can contain backslashes. On Windows, backslashes are directory separators. Git did not use to refuse to write out tracked files with such filenames.