CVE-2021-43816 | Improper Preservation of Permissions in containerd

Exp

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.

Published: 2022-01-05 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-43816 is rated High Exploit Risk (74.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.69%). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.54% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-43816

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-43816

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.15% 1.69% +1.54%
2 2025-11-21 0.67% 0.15% -0.52%
3 2025-11-18 — 0.67% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-43816

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.0 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.3 6.0 [email protected]
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.3 6.0 [email protected]
6.0 2.0 MEDIUM
AV:N/AC:M/Au:S/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.8 6.4 [email protected]

Weakness enumeration for CVE-2021-43816

GitHub Security Advisory for CVE-2021-43816

GHSA-mvff-h3cj-wj9c · Severity: high · Ecosystem: go — Unprivileged pod using `hostPath` can side-step active LSM when it is SELinux

OS Trackers for CVE-2021-43816

vendor priority summary link
alpine critical CVE-2021-43816: 1 source package rows (containerd); 13 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 6. https://security.alpinelinux.org/vuln/CVE-2021-43816
debian unimportant CVE-2021-43816 unimportant priority: Debian including 1 source packages (containerd), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-43816
redhat high — https://access.redhat.com/security/cve/CVE-2021-43816
suse high CVE-2021-43816 severity important: SUSE including 2 source package names (containerd, containerd-ctr), 39 product×package rows across 26 product lines (SUSE CaaS Platform 4.0, SUSE CaaS Platform 4.5, … (26 product lines)): Known Not Affected 39. https://www.suse.com/security/cve/CVE-2021-43816/
ubuntu low CVE-2021-43816 low priority: Ubuntu including 1 source packages (containerd), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 12, ignored 2, needed 1. https://ubuntu.com/security/CVE-2021-43816

Affected software / configurations for CVE-2021-43816

Vendor Product Version Raw CPE
linuxfoundation containerd >= 1.5.1, < 1.5.9 cpe:2.3:a:linuxfoundation:containerd:*:*:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:-:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:beta0:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:beta1:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:beta2:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:beta3:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:beta4:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:rc0:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:rc1:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:rc2:*:*:*:*:*:*
linuxfoundation containerd 1.5.0 cpe:2.3:a:linuxfoundation:containerd:1.5.0:rc3:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
fedoraproject fedora 35 cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*

References for CVE-2021-43816

cvelogic Threat Intelligence