CVE-2021-4001: Linux Kernel

Medium severity, CVSS 4.1. EPSS: 0.2% chance of exploitation in the next 30 days.

A race condition was found in the Linux kernel's ebpf verifier between bpf_map_update_elem and bpf_map_freeze due to a missing lock in kernel/bpf/syscall.c. In this flaw, a local user with a special privilege (cap_sys_admin or cap_bpf) can modify the frozen mapped address space. This flaw affects kernel versions prior to 5.16 rc2.

Affected products

• Linux Linux Kernel: up to and including 5.15; version 5.16 only

Published 2022-01-21. Last modified 2026-10-08.