Vulnerability in Containerd
CVE-2021-43816
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 · last modified .
CVSS v3 metric
CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.017 (76.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 76.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000
Affected products
- Containerd — versions >= 1.5.0, < 1.5.9
- Linuxfoundation Containerd — versions 1.5.0
- Fedoraproject Fedora — versions 34, 35
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/containerd/containerd/security/advisories/GHSA-mvff-h3cj-wj9c (Third Party Advisory)
- github.com/containerd/containerd/issues/6194 (Exploit, Third Party Advisory, Issue Tracking)
- github.com/containerd/containerd/commit/a731039238c62be081eb8c31525b988415745eea (Patch, Third Party Advisory)
- github.com/dweomer/containerd/commit/f7f08f0e34fb97392b0d382e58916d6865100299 (Patch, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
Frequently asked questions
- What is CVE-2021-43816?
- CVE-2021-43816 is a high-severity vulnerability in Containerd, classified under Improper Preservation of Permissions. CVSS score: 8.0/10. Published 2022-01-05.
- How severe is CVE-2021-43816?
- High severity. CVSS v3 base score is 8.0 out of 10.
- Is CVE-2021-43816 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.