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Fencer Vulns
medium 5.5

CVE-2021-3669 json

A flaw was found in the Linux kernel.

published 2022-08-26 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26961

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 22%
public exploits
0
none known

Summary

A flaw was found in the Linux kernel. Measuring usage of the shared memory does not scale with large shared memory segment counts which could lead to resource exhaustion and DoS.

Patch / fix

  • linux linux_kernel 5.15
  • linux Debian 14, Debian 13, Debian 12 5.15.3-1

debian advisories DEBIAN-CVE-2021-3669

  • linux Ubuntu 18.04 LTS 4.15.0-208.220
  • linux Ubuntu 20.04 LTS 5.4.0-146.163
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1153.166
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1099.107
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1102.111
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1096.103
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1046.51
  • linux-iot Ubuntu 20.04 LTS 5.4.0-1013.15

ubuntu advisories UBUNTU-CVE-2021-3669

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

  • kmod SLE Module for Basesystem 15 SP2, SLE Micro 5.0 25-6.10.1
  • kernel-syms SLE Module for Development Tools 15 SP2 5.3.18-24.86.1
  • kernel-source SLE Module for Development Tools 15 SP2, SLE Module for Basesystem 15 SP2 5.3.18-24.86.2
  • kernel-default SLE Workstation Extension 15 SP2, SLE Module for Legacy 15 SP2, SLE Module for Basesystem 15 SP2 +3 more 5.3.18-24.86.2
  • kernel-preempt SLE Workstation Extension 15 SP2, SLE Module for Development Tools 15 SP2, SLE Module for Basesystem 15 SP2 5.3.18-24.86.2
  • perl-Bootloader SLE Module for Development Tools 15 SP2, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 0.931-3.5.1
  • kernel-obs-build SLE Module for Development Tools 15 SP2 5.3.18-24.86.2
  • kernel-default-base SLE Module for Basesystem 15 SP2, SLE Micro 5.0 5.3.18-24.86.2.9.40.2

suse advisories SUSE-SU-2021:3447-1SUSE-SU-2021:3415-1SUSE-SU-2021:3387-1SUSE-SU-2021:3339-1SUSE-SU-2021:3338-1SUSE-SU-2021:3337-1

  • kmod openSUSE Leap 15.2 25-lp152.8.3.1
  • kmod-testsuite openSUSE Leap 15.2 25-lp152.8.3.2
  • kernel-syms openSUSE Leap 15.2 5.3.18-lp152.95.1
  • kernel-obs-qa openSUSE Leap 15.2 5.3.18-lp152.95.1
  • kernel-source openSUSE Leap 15.2 5.3.18-lp152.95.1
  • kernel-default openSUSE Leap 15.2 5.3.18-lp152.95.1
  • kernel-preempt openSUSE Leap 15.2 5.3.18-lp152.95.1
  • kernel-kvmsmall openSUSE Leap 15.2 5.3.18-lp152.95.1

opensuse advisories openSUSE-SU-2021:1365-1openSUSE-SU-2021:1357-1openSUSE-SU-2021:3447-1openSUSE-SU-2021:3387-1openSUSE-SU-2021:3338-1

  • 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

  • kernel CBL-Mariner 2.0 5.15.70.1-1
  • kernel Azure Linux 3.0 6.6.35.1-4

azure linux advisories AZL-10676AZL-34859

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

  • linux-lts Arch Linux 5.15.2-1

arch linux advisories AVG-1741

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-2021-3669 updated cvss 5.5

kernel: reading /proc/sysvipc/shm does not scale with large shared memory segment counts

  • 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, kernel-alt, python-perf, +9 more
    affected: workaround, no fix planned “Out of support scope”
  • 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 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

0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • n/a kernel

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-770 Allocation of Resources Without Limits or Throttling
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.

CPEs and fixed versions use Anchore's correction of NVD's data: Update affected version constraints.