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.

Database specific

{
    "unresolved_ranges": [
        {
            "source": "CPE_FIELD",
            "cpe": "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*",
            "extracted_events": [
                {
                    "last_affected": "9.0"
                }
            ]
        }
    ]
}

References

Affected packages

Git / github.com/opencontainers/runc

Affected ranges

Type

GIT

Repo

https://github.com/opencontainers/runc

Events

Introduced

Fixed

f46b6ba2c9314cfc8caae24a32ec5fe9ef1059fe

Fixed

9c444070ec7bb83995dbc0185da68284da71c554

Fixed

d72d057ba794164c3cce9451a00b72a78b25e1ae

Fixed

f50369af4b571e358f20b139eea52d612eb55eed

Database specific

{
    "source": [
        "CPE_FIELD",
        "REFERENCES"
    ],
    "cpe": "cpe:2.3:a:linuxfoundation:runc:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "1.0.3"
        }
    ]
}

Affected versions

v0.*

v0.0.1

v0.0.2

v0.0.3

v0.0.4

v0.0.5

v0.0.6

v0.0.7

v0.0.8

v1.*

v1.0.0

v1.0.0-rc2

Database specific

vanir_signatures

[
    {
        "target": {
            "function": "nsexec",
            "file": "libcontainer/nsenter/nsexec.c"
        },
        "signature_type": "Function",
        "id": "CVE-2021-43784-05c80d56",
        "source": "https://github.com/opencontainers/runc/commit/9c444070ec7bb83995dbc0185da68284da71c554",
        "signature_version": "v1",
        "deprecated": false,
        "digest": {
            "function_hash": "233434118395672720947136633043365288477",
            "length": 8787.0
        }
    },
    {
        "target": {
            "file": "libcontainer/nsenter/nsexec.c"
        },
        "signature_type": "Line",
        "id": "CVE-2021-43784-2c3fa50a",
        "source": "https://github.com/opencontainers/runc/commit/9c444070ec7bb83995dbc0185da68284da71c554",
        "signature_version": "v1",
        "deprecated": false,
        "digest": {
            "threshold": 0.9,
            "line_hashes": [
                "234646473657006138612640343048962647746",
                "327356145159789987783400882751323863282",
                "90239315903251214012594724923803807455",
                "198183116556879067447228165690972428964",
                "339963725796193190430944059414797272701",
                "142202316579914423472301221805436293431",
                "231209446964619226269402741553096594341",
                "32515865708987726942589308920036595284",
                "213051237322423939483007602968124653302",
                "287960326817347279384680290553971304189",
                "293830033075452282703018818708163348105",
                "161328237504223570740100446455609183954",
                "147099854759317355006340422556916431729",
                "30258751639479763655501433155301258916",
                "105505061053833961194556125824404427858",
                "212796274726232809282656264245566781230",
                "186222305441171549969658422132540548718",
                "339834522181515706816162910118025342049",
                "61004726423031854248653965962142072518",
                "92501804373775289937892463860701853347",
                "333189026463311332189094007788849926815",
                "213043235157353488768314210772726520178",
                "221891607560060652791335033970492692614",
                "336133695759459936561432372455212316104",
                "99978891143355123428593943084189441830",
                "316796549607355859371525105012194813761",
                "163648851550094317347811067854424284808",
                "235848651446313349003948006044716458180",
                "205753705526613566590525004343112630166"
            ]
        }
    },
    {
        "target": {
            "function": "nl_parse",
            "file": "libcontainer/nsenter/nsexec.c"
        },
        "signature_type": "Function",
        "id": "CVE-2021-43784-5b34a02a",
        "source": "https://github.com/opencontainers/runc/commit/9c444070ec7bb83995dbc0185da68284da71c554",
        "signature_version": "v1",
        "deprecated": false,
        "digest": {
            "function_hash": "162980013065698137816975568585436656416",
            "length": 1739.0
        }
    }
]

source

"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2021-43784.json"

vanir_signatures_modified

"2026-04-12T03:54:30Z"