Use-after-free in Linux kernel - CVE-2019-20934

Vulnerability identifier: #VU55260

CSH Severity: Low

CVSS v4: 5.8 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2019-20934

CWE-ID: CWE-416

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error in Linux fair scheduler within the show_numa_stats() function, caused by improperly freed NUMA fault statistics. A local user can trigger a use-after-free error and escalate privileges on the system.

Linux kernel
CentOS
Red Hat Enterprise Linux Workstation
Red Hat Enterprise Linux for Real Time for NFV
Red Hat Enterprise Linux for Real Time
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for Scientific Computing
Red Hat Enterprise Linux for Power, big endian
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux Desktop
Red Hat Enterprise Linux Server
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux Server - TUS
kernel (Red Hat package)
kernel-rt (Red Hat package)
Session Smart Router

Install updates from vendor's website.

Linux kernel - update to 5.2.6
kernel (Red Hat package) - addressed in versions 3.10.0-1062.59.1.el7, 3.10.0-1160.36.2.el7
kernel-rt (Red Hat package) - update to 3.10.0-1160.36.2.rt56.1179.el7
Session Smart Router - addressed in versions 5.4.7, 5.5.3

• https://bugs.chromium.org/p/project-zero/issues/detail?id=1913
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.2.6
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=16d51a590a8ce3befb1308e0e7ab77f3b661af33

• Privilege escalation in Linux kernel on NUMA systems
• Red Hat Enterprise Linux 7 update for kernel
• Red Hat Enterprise Linux 7 update for kernel-rt
• CentOS 7 update for kernel
• Multiple vulnerabilities in Juniper Networks Session Smart Router
• Red Hat Enterprise Linux 7 update for kernel