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CVE-2021-4001

4.1 · MEDIUM

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.

Published Jan 21, 2022CWE-367EPSS 0.19%

Overview

CVE-2021-4001 is a medium-severity vulnerability. It was published on January 21, 2022 and has a CVSS 3.1 base score of 4.1 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.1, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refbugzilla.redhat.com/show_bug.cgi?id=2025645Refgit.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=353050be4c19e102178ccc05988101887c25ae53Refbugzilla.redhat.com/show_bug.cgi?id=2025645Refgit.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=353050be4c19e102178ccc05988101887c25ae53

How CyberStrike helps

Frequently asked questions

What is CVE-2021-4001?

CVE-2021-4001 is a medium-severity vulnerability. It was published on January 21, 2022 and has a CVSS 3.1 base score of 4.1 (MEDIUM).

How severe is CVE-2021-4001?

This vulnerability has a CVSS 3.1 base score of 4.1, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-4001?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-4001?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-4001 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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