CVE-2021-4001

Name: CVE-2021-4001
Creator: NVD / NIST
Published: 2022-01-21T19:15:09.703+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.1/10EPSS 0.19%

Last modified Jun 17, 2026

CVE-2021-4001 is a medium-severity vulnerability rated 4.1/10 on the CVSS scale. 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. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

4.1/10

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

0.19%

8.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	<= 5.15	—
Linux	Linux Kernel	5.16	Rc1

References

https://bugzilla.redhat.com/show_bug.cgi?id=2025645Issue Tracking, Patch, Third Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=353050be4c19e102178ccc05988101887c25ae53Patch, Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2025645Issue Tracking, Patch, Third Party Advisory
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=353050be4c19e102178ccc05988101887c25ae53Patch, Third Party Advisory

Timeline

Published: Jan 21, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-4001?

How severe is CVE-2021-4001?

CVE-2021-4001 has a CVSS score of 4.1/10 (MEDIUM severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.

How do I fix CVE-2021-4001?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-4001?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST