Vulnerability in Linux Kernel
CVE-2021-4001
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.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.1 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (7.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Linux Kernel — versions 5.16
- Kernel — versions kernel 5.16 rc2
Weakness classification (CWE)
References
- bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
- git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/ (Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-4001?
- CVE-2021-4001 is a medium-severity vulnerability in Linux Kernel, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 4.1/10. Published 2022-01-21.
- How severe is CVE-2021-4001?
- Medium severity. CVSS v3 base score is 4.1 out of 10.