CVE-2019-13272: Linux Kernel Improper Privilege Management Vulnerability

A flaw was found in the way PTRACETRACEME functionality was handled in the Linux kernel. The kernel's implementation of ptrace can inadvertently grant elevated permissions to an attacker who can then abuse the relationship between the tracer and the process being traced. This flaw could allow a local, unprivileged user to increase their privileges on the system or cause a denial of service.

In the Linux kernel before 5.1.17, ptracelink in kernel/ptrace.c mishandles the recording of the credentials of a process that wants to create a ptrace relationship, which allows local users to obtain root access by leveraging certain scenarios with a parent-child process relationship, where a parent drops privileges and calls execve (potentially allowing control by an attacker). One contributing factor is an object lifetime issue (which can also cause a panic). Another contributing factor is incorrect marking of a ptrace relationship as privileged, which is exploitable through (for example) Polkit's pkexec helper with PTRACETRACEME. NOTE: SELinux denyptrace might be a usable workaround in some environments.

Kernel/ptrace.c in Linux kernel mishandles contains an improper privilege management vulnerability that allows local users to obtain root access.

— CISA