Vulnerability CVE-2021-43816

Vulnerability Name:

CVE-2021-43816 (CCN-216854)

Assigned:

2021-11-16

Published:

2022-01-05

Updated:

2022-04-01

Summary:

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 v3 Severity:

9.1 Critical (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H)
7.9 High (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): Low Privileges Required (PR): High User Interaction (UI): None
Scope:	Scope (S): Changed
Impact Metrics:	Confidentiality (C): High Integrity (I): High Availibility (A): High

8.0 High (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H)
7.0 High (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): High Privileges Required (PR): High User Interaction (UI): None
Scope:	Scope (S): Changed
Impact Metrics:	Confidentiality (C): High Integrity (I): High Availibility (A): High

CVSS v2 Severity:

6.0 Medium (CVSS v2 Vector: AV:N/AC:M/Au:S/C:P/I:P/A:P)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): Medium Authentication (Au): Single_Instance
Impact Metrics:	Confidentiality (C): Partial Integrity (I): Partial Availibility (A): Partial

7.1 High (CCN CVSS v2 Vector: AV:N/AC:H/Au:S/C:C/I:C/A:C)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): High Athentication (Au): Single_Instance
Impact Metrics:	Confidentiality (C): Complete Integrity (I): Complete Availibility (A): Complete