Critical severity · published Jan 5, 2022
CVE-2021-43816
containerd is an open source container runtime
9.1
CVSS
1.7%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)1.7% · higher than 77% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
Containerd · Linuxfoundation
1.5.1 before 1.5.9; 1.5.0; 1.5.0; 1.5.0; 1.5.0; 1.5.0; +5 more · source: NVD
FE
Fedora · Fedoraproject
34; 35 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-43816
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-43816
Patch
https://github.com/containerd/containerd/commit/a731039238c62be081eb8c31525b988415745eea
Exploit
https://github.com/containerd/containerd/issues/6194
Third Party Advisory
https://github.com/containerd/containerd/security/advisories/GHSA-mvff-h3cj-wj9c
Patch
https://github.com/dweomer/containerd/commit/f7f08f0e34fb97392b0d382e58916d6865100299
lists.fedoraproject.org
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GD5GH7NMK5VJMA2Y5CYB5O5GTPYMWMLX/
lists.fedoraproject.org
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MPDIZMI7ZPERSZE2XO265UCK5IWM7CID/
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