CVE-2021-43784

CVE Details

Release Date:

2021-12-06

Description

runc is a CLI tool for spawning and running containers on Linux according to the OCI specification. In runc, netlink is used internally as a serialization system for specifying the relevant container configuration to the `C` portion of the code (responsible for the based namespace setup of containers). In all versions of runc prior to 1.0.3, the encoder did not handle the possibility of an integer overflow in the 16-bit length field for the byte array attribute type, meaning that a large enough malicious byte array attribute could result in the length overflowing and the attribute contents being parsed as netlink messages for container configuration. This vulnerability requires the attacker to have some control over the configuration of the container and would allow the attacker to bypass the namespace restrictions of the container by simply adding their own netlink payload which disables all namespaces. The main users impacted are those who allow untrusted images with untrusted configurations to run on their machines (such as with shared cloud infrastructure). runc version 1.0.3 contains a fix for this bug. As a workaround, one may try disallowing untrusted namespace paths from your container. It should be noted that untrusted namespace paths would allow the attacker to disable namespace protections entirely even in the absence of this bug.

See more information about CVE-2021-43784 from MITRE CVE dictionary and NIST NVD

CVSS v3.0 metrics

NOTE: The following CVSS v3.0 metrics and score provided are preliminary and subject to review.

Base Score:	5	Base Metrics:	AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
Access Vector:	Network	Attack Complexity:	High
Privileges Required:	Low	User Interaction:	None
Scope:	Unchanged	Confidentiality Impact:	Low
Integrity Impact:	Low	Availability Impact:	Low

Errata information

Platform	Errata	Release Date
Oracle Linux version 9 (runc)	ELSA-2023-6380	2023-11-11

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