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Fencer Vulns
high 7.1

CVE-2021-3739 json

A NULL pointer dereference flaw was found in the btrfs_rm_device function in fs/btrfs/volumes.c in the Linux Kernel, where triggering the b…

published 2022-03-07 4 y ago modified 2026-09-01 2 mo ago also EUVD-2021-27015

cvss
7.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

A NULL pointer dereference flaw was found in the btrfs_rm_device function in fs/btrfs/volumes.c in the Linux Kernel, where triggering the bug requires ‘CAP_SYS_ADMIN’. This flaw allows a local attacker to crash the system or leak kernel internal information. The highest threat from this vulnerability is to system availability.

Patch / fix

  • linux linux_kernel 5.4.144, 5.10.62, 5.13.14, 5.14.1
  • linux Debian 14, Debian 13, Debian 12 5.14.6-1

debian advisories DEBIAN-CVE-2021-3739

  • linux Ubuntu 20.04 LTS 5.4.0-90.101
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1059.62
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1057.61
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1055.58
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1007.8
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1049.51
  • linux-azure Ubuntu 20.04 LTS 5.4.0-1063.66
  • linux-gkeop Ubuntu 20.04 LTS 5.4.0-1026.27

ubuntu advisories UBUNTU-CVE-2021-3739

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt SLE Micro 5.1, Real Time Module 15 SP3 5.3.18-57.1
  • kernel-syms-rt Real Time Module 15 SP3 5.3.18-57.1
  • kernel-rt_debug Real Time Module 15 SP3 5.3.18-57.1
  • kernel-source-rt Real Time Module 15 SP3 5.3.18-57.1
  • kernel-default SLE Workstation Extension 15 SP3, SLE Module for Legacy 15 SP3, SLE Module for Basesystem 15 SP3 +3 more 5.3.18-59.24.1
  • kernel-default-base SLE Module for Basesystem 15 SP3, SLE Micro 5.1 5.3.18-59.24.1.18.12.1
  • kernel-syms SLE Module for Development Tools 15 SP2 5.3.18-24.83.1
  • kernel-source SLE Module for Development Tools 15 SP2, SLE Module for Basesystem 15 SP2 5.3.18-24.83.1

suse advisories SUSE-SU-2021:3415-1SUSE-SU-2021:3205-2SUSE-SU-2021:3207-1SUSE-SU-2021:3205-1SUSE-SU-2021:3179-1SUSE-SU-2021:3178-1

  • dtb-aarch64 openSUSE Leap 15.3 5.3.18-59.24.1
  • kernel-64kb openSUSE Leap 15.3 5.3.18-59.24.1
  • kernel-syms openSUSE Leap 15.3 5.3.18-59.24.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.24.1
  • kernel-source openSUSE Leap 15.3 5.3.18-59.24.1
  • kernel-default openSUSE Leap 15.3 5.3.18-59.24.1
  • kernel-preempt openSUSE Leap 15.3 5.3.18-59.24.1
  • kernel-kvmsmall openSUSE Leap 15.3 5.3.18-59.24.1

opensuse advisories openSUSE-SU-2021:3205-1openSUSE-SU-2021:3179-1openSUSE-SU-2021:1271-1

  • linux Arch Linux 5.14.2.arch1-2
  • linux-zen Arch Linux 5.14.2.zen1-2
  • linux-hardened Arch Linux 5.13.14.hardened1-1
  • linux-lts Arch Linux 5.10.62-1

arch linux advisories AVG-2346AVG-2347AVG-2348AVG-2349

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3739 updated cvss 6.2

kernel: null-ptr-dereference bug in btrfs_rm_device in fs/btrfs/volumes.c

  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/torvalds/linux/commit/e4571b8c5e9ffa1e85c0c671995bd4dcc5c75091 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
NVD 2.0 3.6 AV:L/AC:L/Au:N/C:P/I:N/A:P

Affected products

  • n/a kernel

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.