CVE-2020-14351: 
Linux Kernel vulnerability analysis and mitigation

CVE-2020-14351 is a use-after-free memory vulnerability discovered in the Linux kernel's perf subsystem. The vulnerability was disclosed in September 2020 and affects the performance monitoring functionality of Linux systems. The flaw allows a local attacker with permission to monitor perf events to corrupt memory and potentially escalate privileges (Ubuntu Security, NVD).

The vulnerability stems from a race condition in the perf subsystem of the Linux kernel that leads to a use-after-free condition. The issue affects systems where users have permission to monitor perf events, either through CAP_SYS_ADMIN capabilities or through modifications to /proc/sys/kernel/perf_event_paranoid. The vulnerability has been assigned a CVSS 3 Severity Score of 7.8 (High) (Ubuntu Security, Red Hat Bugzilla).

The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability. If exploited, the vulnerability could allow an attacker to cause a denial of service through system crashes, corrupt memory, or potentially escalate privileges on the system (CVE Mitre, Red Hat Bugzilla).

While there is no way to disable the perf subsystem on Linux systems, the vulnerability can be mitigated by reducing or removing users' access to perf events. The upstream kernel documentation provides guidance on securing perf access through the perf_event_paranoid setting and recommends creating a perf_users group instead of modifying the default security settings. For systems running Debian, the default kernel configuration does not allow unprivileged users to access performance events, which fully mitigates this issue (Red Hat Bugzilla, Debian Security).