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Bug 828471 (CVE-2021-43784) - <app-containers/runc-1.0.2-r1: Access restriction bypass (CVE-2021-43784)
Summary: <app-containers/runc-1.0.2-r1: Access restriction bypass (CVE-2021-43784)
Alias: CVE-2021-43784
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Linux
: Normal minor (vote)
Assignee: Gentoo Security
Whiteboard: B3 [glsa?]
Depends on:
Reported: 2021-12-06 19:23 UTC by Sam James
Modified: 2022-01-01 10:26 UTC (History)
2 users (show)

See Also:
Package list:
Runtime testing required: ---


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Description Sam James archtester Gentoo Infrastructure gentoo-dev Security 2021-12-06 19:23:35 UTC
CVE-2021-43784 (

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.
Comment 1 Larry the Git Cow gentoo-dev 2021-12-14 08:41:47 UTC
The bug has been referenced in the following commit(s):

commit 49df66c342189a9408855b6ab29403b459ebb39d
Author:     Georgy Yakovlev <>
AuthorDate: 2021-12-14 08:39:33 +0000
Commit:     Georgy Yakovlev <>
CommitDate: 2021-12-14 08:41:10 +0000

    app-emulation/runc: revbump for CVE-2021-43784
    since we pin dep of runc to exact version in stack, adding 1.0.3
    will require revbumping the rest.
    So let's just revbump stable ebuild with a patch from upstream
    release branch.
    Signed-off-by: Georgy Yakovlev <>

 app-emulation/runc/files/CVE-2021-43784.patch      | 86 ++++++++++++++++++++++
 .../{runc-1.0.2.ebuild => runc-1.0.2-r1.ebuild}    |  2 +
 2 files changed, 88 insertions(+)