A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copypagetoiterpipe and pushpipe functions in the Linux kernel and could thus contain stale values. An unprivileged local user could use this flaw to write to pages in the page cache backed by read only files and as such escalate their privileges on the system.

A flaw in the kernels implementation of ptrace which could inadvertantly grant elevated permissions to an attacker who could abuse the relationship between tracer and the process being traced.

The mechanism used to link the process requesting the ptrace and the process being ptraced could allow a local user to obtain root level priviledges by creating an opportunity to abuse the frequently used pattern of dropping privileges and then execve a child with reduced privileges/permissions.

References: https://bugs.chromium.org/p/project-zero/issues/detail?id=1903 https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.1.17 https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6994eefb0053799d2e07cd140df6c2ea106c41ee https://github.com/torvalds/linux/commit/6994eefb0053799d2e07cd140df6c2ea106c41ee