CVE-2021-43816
Last modified
CVE-2021-43816 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. 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). EPSS estimates a 1.69% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Linuxfoundation | Containerd | >= 1.5.1, < 1.5.9 |
| Linuxfoundation | Containerd | 1.5.0 |
| Fedoraproject | Fedora | 34 |
| Fedoraproject | Fedora | 35 |
References
- https://github.com/containerd/containerd/commit/a731039238c62be081eb8c31525b988415745eeaPatch, Third Party Advisory
- https://github.com/containerd/containerd/issues/6194Exploit, Issue Tracking, Third Party Advisory
- https://github.com/containerd/containerd/security/advisories/GHSA-mvff-h3cj-wj9cThird Party Advisory
- https://github.com/dweomer/containerd/commit/f7f08f0e34fb97392b0d382e58916d6865100299Patch, Third Party Advisory
- https://github.com/containerd/containerd/commit/a731039238c62be081eb8c31525b988415745eeaPatch, Third Party Advisory
- https://github.com/containerd/containerd/issues/6194Exploit, Issue Tracking, Third Party Advisory
- https://github.com/containerd/containerd/security/advisories/GHSA-mvff-h3cj-wj9cThird Party Advisory
- https://github.com/dweomer/containerd/commit/f7f08f0e34fb97392b0d382e58916d6865100299Patch, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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