CVE-2021-43784

Vulnerability 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.

CVSS Score

Affected Products

Related Weaknesses (CWE)

References

• https://bugs.chromium.org/p/project-zero/issues/detail?id=2241ExploitThird Party Advisory
• https://github.com/opencontainers/runc/commit/9c444070ec7bb83995dbc0185da68284daPatchThird Party Advisory
• https://github.com/opencontainers/runc/commit/d72d057ba794164c3cce9451a00b72a78bPatchThird Party Advisory
• https://github.com/opencontainers/runc/commit/f50369af4b571e358f20b139eea52d612ePatchThird Party Advisory
• https://github.com/opencontainers/runc/security/advisories/GHSA-v95c-p5hm-xq8fPatchThird Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/12/msg00005.htmlVendor Advisory
• https://lists.debian.org/debian-lts-announce/2024/02/msg00005.html
• https://bugs.chromium.org/p/project-zero/issues/detail?id=2241ExploitThird Party Advisory
• https://github.com/opencontainers/runc/commit/9c444070ec7bb83995dbc0185da68284daPatchThird Party Advisory
• https://github.com/opencontainers/runc/commit/d72d057ba794164c3cce9451a00b72a78bPatchThird Party Advisory
• https://github.com/opencontainers/runc/commit/f50369af4b571e358f20b139eea52d612ePatchThird Party Advisory
• https://github.com/opencontainers/runc/security/advisories/GHSA-v95c-p5hm-xq8fPatchThird Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/12/msg00005.htmlVendor Advisory
• https://lists.debian.org/debian-lts-announce/2024/02/msg00005.html