CVE-2021-43816
HIGHEPSS 76th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
Exploit Intelligence
Elevated risk: more likely to be exploited than 76% of all known CVEs.
References
Related Vulnerabilities
Other CWE-281 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-8543 | Critical | 9.8 | 74% | KEV | - |
| CVE-2019-0233 | High | 7.5 | 68% | - | - |
| CVE-2017-8589 | Critical | 9.8 | 26% | - | - |
| CVE-2021-33990 | Critical | 9.8 | 12% | - | - |
| CVE-2017-8563 | High | 8.1 | 7.2% | - | - |
| CVE-2017-8578 | High | 7.8 | 6.5% | - | - |
Common questions
How do I fix CVE-2021-43816?
Upgrade containerd on debian 12 to 1.5.9~ds1-1 or later.
Is CVE-2021-43816 being actively exploited?
Not that we know of. CVE-2021-43816 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 1.7% is the estimated probability that it will be exploited in the next 30 days. That is higher than 76% of all scored CVEs.
How severe is CVE-2021-43816?
CVE-2021-43816 has a CVSS v3 base score of 8.0, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-43816 affect?
Published advisories record a fix for containerd (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.