CVE-2021-43816Public exploitNetwork attack vector

Host file read and write via SELinux relabeling

Published Jan 5, 2022 · Updated Apr 22, 2025

Improper permission preservation in containerd 1.5.0 through 1.5.8 allows remote authenticated users to read and write host files. The CRI container creation path indiscriminately relabels hostPath sources mounted at /etc/hosts, /etc/hostname, or /etc/resolv.conf with the container process SELinux label. Exploitation requires Linux with SELinux, the CRI plugin, pod-creation access, and a crafted bind mount; affected files can be read or changed but not deleted.

CVSS severity9.1
Critical
EPSS probability1.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper permission preservation in containerd 1.5.0 through 1.5.8 allows remote authenticated users to read and write host files. The CRI container creation path indiscriminately relabels hostPath sources mounted at /etc/hosts, /etc/hostname, or /etc/resolv.conf with the container process SELinux label. Exploitation requires Linux with SELinux, the CRI plugin, pod-creation access, and a crafted bind mount; affected files can be read or changed but not deleted.

The record

CVE
CVE-2021-43816
Published
Jan 5, 2022
Updated
Apr 22, 2025
Vendor
containerd
Product
containerd
Classifications
CWE-281, T1611
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 5, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.5.0, < 1.5.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

containerd · containerdversion=>= 1.5.0, < 1.5.9

Published CVSS scores

8.0GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
6.0NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-281Improper Preservation of Permissions
T1611Escape to Host

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo