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Fencer Vulns
medium 6.7

CVE-2021-0941 json

In bpf_skb_change_head of filter.c, there is a possible out of bounds read due to a use after free.

published 2021-10-25 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-3560

cvss
6.7
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits
0
none known

Summary

In bpf_skb_change_head of filter.c, there is a possible out of bounds read due to a use after free. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-154177719References: Upstream kernel

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.10.28-1

debian advisories DEBIAN-CVE-2021-0941

  • linux Ubuntu 18.04 LTS 4.15.0-144.148
  • linux Ubuntu 20.04 LTS 5.4.0-74.83
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1103.110
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1049.51
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1044.47
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1044.46
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1092.94
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1040.41

ubuntu advisories UBUNTU-CVE-2021-0941

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 RHEL 8 4.18.0-372.9.1.el8
  • perf RHEL 8 4.18.0-372.9.1.el8
  • bpftool RHEL 8 4.18.0-372.9.1.el8
  • kernel-core RHEL 8 4.18.0-372.9.1.el8
  • kernel-tools RHEL 8 4.18.0-372.9.1.el8
  • python3-perf RHEL 8 4.18.0-372.9.1.el8
  • kernel-modules RHEL 8 4.18.0-372.9.1.el8
  • kernel-zfcpdump RHEL 8 4.18.0-372.9.1.el8

red hat advisories RHSA-2022:1988RHSA-2022:1975

  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.70.2
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.70.2
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.70.2
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.70.2
  • kernel-rt SLE Micro 5.1, Real Time Module 15 SP3 5.3.18-65.2
  • kernel-syms-rt Real Time Module 15 SP3 5.3.18-65.1
  • kernel-rt_debug Real Time Module 15 SP3 5.3.18-65.2
  • kernel-source-rt Real Time Module 15 SP3 5.3.18-65.2

suse advisories SUSE-SU-2021:4099-1SUSE-SU-2021:4090-1SUSE-SU-2021:4038-1SUSE-SU-2021:4021-1SUSE-SU-2021:3992-1SUSE-SU-2021:3979-1

  • dtb-aarch64 openSUSE Leap 15.3 5.3.18-59.37.1
  • kernel-64kb openSUSE Leap 15.3 5.3.18-59.37.2
  • kernel-syms openSUSE Leap 15.3 5.3.18-59.37.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.37.1
  • kernel-source openSUSE Leap 15.3 5.3.18-59.37.2
  • kernel-default openSUSE Leap 15.3 5.3.18-59.37.2
  • kernel-preempt openSUSE Leap 15.3 5.3.18-59.37.2
  • kernel-kvmsmall openSUSE Leap 15.3 5.3.18-59.37.2

opensuse advisories openSUSE-SU-2021:3941-1openSUSE-SU-2021:3876-1openSUSE-SU-2021:3806-1openSUSE-SU-2021:1501-1

  • kernel AlmaLinux 8 4.18.0-372.9.1.el8
  • perf AlmaLinux 8 4.18.0-372.9.1.el8
  • bpftool AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-core AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-tools AlmaLinux 8 4.18.0-372.9.1.el8
  • python3-perf AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-modules AlmaLinux 8 4.18.0-372.9.1.el8
  • kernel-debug-core AlmaLinux 8 4.18.0-372.9.1.el8

almalinux advisories ALSA-2022:1988

  • kernel Rocky Linux 8 4.18.0-372.9.1.el8
  • kernel-rt Rocky Linux 8 4.18.0-372.9.1.rt7.166.el8

rocky linux advisories RLSA-2022:1988RLSA-2022:1975

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-2021-0941 updated cvss 6.7

kernel: out-of-bounds read in bpf_skb_change_head() of filter.c due to a use-after-free

  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-372.9.1.el8, kernel 4.18.0-372.9.1.el8, bpftool 4.18.0-372.9.1.el8, kernel-core 4.18.0-372.9.1.el8, kernel-tools 4.18.0-372.9.1.el8, python3-perf 4.18.0-372.9.1.el8, +15 more Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-372.9.1.el8, kernel-debuginfo-common-aarch64 4.18.0-372.9.1.el8, kernel-debuginfo-common-ppc64le 4.18.0-372.9.1.el8
    fixed: vendor fix RHSA-2022:1988
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-372.9.1.rt7.166.el8, kernel-rt-kvm 4.18.0-372.9.1.rt7.166.el8, kernel-rt-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-kvm 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-core 4.18.0-372.9.1.rt7.166.el8, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-372.9.1.rt7.166.el8, kernel-rt-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules-extra 4.18.0-372.9.1.rt7.166.el8, +2 more
    fixed: vendor fix RHSA-2022:1975
  • 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 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

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.7 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • n/a Android

Classification

Weakness

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.