A use-after-free flaw was found in cgroup1_parse_param in kernel/cgroup/cgroup-v1.c in the Linux kernel's cgroup v1 parser.

published 2022-02-04 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-34022

cvss: 8.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.2%; EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits: 0; none known

A use-after-free flaw was found in cgroup1_parse_param in kernel/cgroup/cgroup-v1.c in the Linux kernel's cgroup v1 parser. A local attacker with a user privilege could cause a privilege escalation by exploiting the fsconfig syscall parameter leading to a container breakout and a denial of service on the system.

Patch / fix

fixed in 1 distros 5 links 2

linux linux_kernel 5.4.134, 5.10.52, 5.12.19, 5.13.4

debian ubuntu red hat suse rocky linux

linux Debian 14, Debian 13, Debian 12 5.14.6-1

debian advisories DEBIAN-CVE-2021-4154

linux Ubuntu 20.04 LTS 5.4.0-88.99
linux-aws Ubuntu 20.04 LTS 5.4.0-1057.60
linux-gcp Ubuntu 20.04 LTS 5.4.0-1053.57
linux-gke Ubuntu 20.04 LTS 5.4.0-1053.56
linux-ibm Ubuntu 20.04 LTS 5.4.0-1005.6
linux-kvm Ubuntu 20.04 LTS 5.4.0-1047.49
linux-azure Ubuntu 20.04 LTS 5.4.0-1059.62
linux-gkeop Ubuntu 20.04 LTS 5.4.0-1024.25

ubuntu advisories UBUNTU-CVE-2021-4154

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 4.18.0-348.20.1.el8_5
perf RHEL 8 4.18.0-348.20.1.el8_5
bpftool RHEL 8 4.18.0-348.20.1.el8_5
kernel-core RHEL 8 4.18.0-348.20.1.el8_5
kernel-tools RHEL 8 4.18.0-348.20.1.el8_5
python3-perf RHEL 8 4.18.0-348.20.1.el8_5
kernel-modules RHEL 8 4.18.0-348.20.1.el8_5
kernel-zfcpdump RHEL 8 4.18.0-348.20.1.el8_5

red hat advisories RHSA-2022:0825 RHSA-2022:0841 RHSA-2022:0819 RHSA-2022:0849 RHSA-2022:0231 RHSA-2022:0186

dtb-aarch64 openSUSE Leap 15.4, openSUSE Leap 15.3 5.3.18-150300.59.68.1
kernel-64kb SLE Module for Basesystem 15 SP3, openSUSE Leap 15.3 5.3.18-150300.59.68.1
kernel-syms SLE Module for Development Tools 15 SP3, openSUSE Leap 15.3 5.3.18-150300.59.68.1
kernel-obs-qa openSUSE Leap 15.3 5.3.18-150300.59.68.1
kernel-source SLE Module for Development Tools 15 SP3, SLE Module for Basesystem 15 SP3, openSUSE Leap 15.3 5.3.18-150300.59.68.1
kernel-default SLE Workstation Extension 15 SP3, SLE Module for Legacy 15 SP3, SLE Module for Basesystem 15 SP3 +5 more 5.3.18-150300.59.68.1
kernel-preempt SLE Workstation Extension 15 SP3, SLE Module for Development Tools 15 SP3, SLE Module for Basesystem 15 SP3 +2 more 5.3.18-150300.59.68.1
kernel-kvmsmall openSUSE Leap 15.3 5.3.18-150300.59.68.1

suse advisories SUSE-SU-2022:1687-1 SUSE-SU-2022:1676-1 SUSE-SU-2022:1669-1 SUSE-SU-2022:0295-1 SUSE-SU-2022:0293-1 SUSE-SU-2022:0292-1

kernel Rocky Linux 8 4.18.0-348.20.1.el8_5
kernel-rt Rocky Linux 8 4.18.0-348.20.1.rt7.150.el8_5

rocky linux advisories RLSA-2022:0825 RLSA-2022:0819

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-2021-4154 updated 2026-11-07 cvss 8.8

kernel: local privilege escalation by exploiting the fsconfig syscall parameter leads to container breakout

Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-348.20.1.el8_5, kernel-debuginfo-common-aarch64 4.18.0-348.20.1.el8_5, kernel-debuginfo-common-ppc64le 4.18.0-348.20.1.el8_5 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-348.20.1.el8_5, kernel 4.18.0-348.20.1.el8_5, bpftool 4.18.0-348.20.1.el8_5, kpatch-patch-4_18_0-348 1-3.el8, kernel-core 4.18.0-348.20.1.el8_5, kernel-tools 4.18.0-348.20.1.el8_5, +19 more
fixed: vendor fix RHSA-2022:0825
Red Hat Enterprise Linux BaseOS EUS (v.8.4) perf 4.18.0-305.34.2.el8_4, kernel 4.18.0-305.34.2.el8_4, bpftool 4.18.0-305.34.2.el8_4, kpatch-patch-4_18_0-305 1-10.el8, kernel-core 4.18.0-305.34.2.el8_4, kernel-tools 4.18.0-305.34.2.el8_4, +25 more Red Hat Enterprise Linux CRB EUS (v.8.4) kernel-debuginfo-common-x86_64 4.18.0-305.34.2.el8_4, kernel-debuginfo-common-aarch64 4.18.0-305.34.2.el8_4, kernel-debuginfo-common-ppc64le 4.18.0-305.34.2.el8_4
fixed: vendor fix RHSA-2022:0186
Red Hat Enterprise Linux for Real Time (v. 8) kernel-rt 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-core 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-modules 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-core 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-modules 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-modules-extra 4.18.0-348.20.1.rt7.150.el8_5, +2 more
fixed: vendor fix RHSA-2022:0819
Red Hat Enterprise Linux NFV EUS (v.8.4) kernel-rt 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-kvm 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-core 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-modules 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-debug-kvm 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-debug-core 4.18.0-305.34.2.rt7.107.el8_4, +4 more
fixed: vendor fix RHSA-2022:0187
Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-kvm 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-core 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-modules 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-kvm 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-core 4.18.0-348.20.1.rt7.150.el8_5, +4 more
fixed: vendor fix RHSA-2022:0819
Red Hat Enterprise Linux RT EUS (v.8.4) kernel-rt 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-core 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-modules 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-debug-core 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-debug-modules 4.18.0-305.34.2.rt7.107.el8_4, kernel-rt-modules-extra 4.18.0-305.34.2.rt7.107.el8_4, +2 more
fixed: vendor fix RHSA-2022:0187
Red Hat Virtualization 4 Hypervisor for RHEL 8 redhat-virtualization-host 4.4.10-202203101736_8.5, redhat-virtualization-host-image-update 4.4.10-202203101736_8.5
fixed: vendor fix RHSA-2022:0841
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 Red Hat RHEL 8-based RHEV-H for RHEV 4 (build requirements) redhat-release-virtualization-host 4.4.10-2.el8ev, redhat-release-virtualization-host-content 4.4.10-2.el8ev, redhat-virtualization-host-image-update-placeholder 4.4.10-2.el8ev
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

1.22% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	8.8	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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 kernel

Classification

Weakness

CWE-416 Use After Free

Technology feeds

Linux kernel rss critical rss

References

git.kernel.org /pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3b0462726e7ef281c35a7a4ae33e93ee2bc9975b
mailing-list, patch, vendor-advisory
bugzilla.redhat.com /show_bug.cgi?id=2034514
issue-tracking, patch, third-party-advisory
cloud.google.com /anthos/clusters/docs/security-bulletins#gcp-2022-002
third-party-advisory
security.netapp.com /advisory/ntap-20220225-0004/
third-party-advisory

Sources

CVE List CVE-2021-4154
NVD CVE-2021-4154

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.

Summary