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Fencer Vulns
high 8.0

CVE-2021-43816 json

Improper Preservation of Permissions in containerd

published 2022-01-05 4 y ago modified 2026-07-08 4 mo ago also GHSA-mvff-h3cj-wj9c , GO-2022-0278 , EUVD-2022-0652

cvss
8.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

containerd is an open source container runtime. On installations using SELinux, such as EL8 (CentOS, RHEL), Fedora, or SUSE MicroOS, with containerd since v1.5.0-beta.0 as the backing container runtime interface (CRI), an unprivileged pod scheduled to the node may bind mount, via hostPath volume, any privileged, regular file on disk for complete read/write access (sans delete). Such is achieved by placing the in-container location of the hostPath volume mount at either `/etc/hosts`, `/etc/hostname`, or `/etc/resolv.conf`. These locations are being relabeled indiscriminately to match the container process-label which effectively elevates permissions for savvy containers that would not normally be able to access privileged host files. This issue has been resolved in version 1.5.9. Users are advised to upgrade as soon as possible.

Patch / fix

  • go github.com/containerd/containerd 1.5.9
  • linuxfoundation containerd 1.5.9
  • containerd Debian 14, Debian 13, Debian 12 1.5.9~ds1-1

debian advisories DEBIAN-CVE-2021-43816

  • containerd Ubuntu 18.04 LTS 1.5.9-0ubuntu1~18.04.1
  • containerd Ubuntu 20.04 LTS 1.5.9-0ubuntu1~20.04.4
  • containerd Ubuntu 22.04 LTS 1.5.9-0ubuntu1

ubuntu advisories UBUNTU-CVE-2021-43816

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

  • containerd Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 1.5.9-r0

alpine advisories ALPINE-CVE-2021-43816

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2021-43816 updated cvss 8.0

containerd: Unprivileged pod may bind mount any privileged regular file on disk

  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/prometheus-rhel9, multicluster-hub-repo-container, multicloud-operators-channel-container, multicloud-operators-subscription-container, multicloud-operators-subscription-release-container
    affected: no fix available
  • Red Hat OpenShift Container Platform 4 openshift, openshift-clients, openshift-kubelet, openshift-hyperkube, openshift-kube-apiserver, openshift-kube-scheduler, +2 more
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat OpenStack Platform 16.2 osp-director-provisioner-container, rhosp-rhel8-tech-preview/osp-director-operator, rhosp-rhel8-tech-preview/osp-director-downloader
    affected: no fix planned “Will not fix”
  • Red Hat OpenShift Developer Tools and Services ocp-tools-4/jenkins-rhel8 Red Hat Advanced Cluster Management for Kubernetes 2 containerd Red Hat OpenShift Container Platform 4 cri-o
    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

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
18 mo ago

Exploit prediction

1.81% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/containerd/containerd/issues/6194 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 6.0 AV:N/AC:M/Au:S/C:P/I:P/A:P
GitHub 3.1 8.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
go github.com/containerd/containerd
>=1.5.0, <1.5.9
1.5.9

Affected products

  • containerd containerd

Classification

Weakness
  • CWE-281 Improper Preservation of Permissions

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.