{"cve":"CVE-2021-43784","nvd":{"published":"2021-12-06T18:15:08.240","modified":"2026-06-17T04:11:25.983","status":"Modified","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L","score":5.0},"cwes":["CWE-190"],"references":["https://bugs.chromium.org/p/project-zero/issues/detail?id=2241","https://github.com/opencontainers/runc/commit/9c444070ec7bb83995dbc0185da68284da71c554","https://github.com/opencontainers/runc/commit/d72d057ba794164c3cce9451a00b72a78b25e1ae","https://github.com/opencontainers/runc/commit/f50369af4b571e358f20b139eea52d612eb55eed","https://github.com/opencontainers/runc/security/advisories/GHSA-v95c-p5hm-xq8f"],"products":["debian:debian_linux","linuxfoundation:runc"],"source":"nvd","synced_at":"2026-10-19T21:25:41.256909649+00:00"},"epss":{"cve":"CVE-2021-43784","score":0.01803,"percentile":0.78539,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-v95c-p5hm-xq8f","url":"https://osv.dev/vulnerability/GHSA-v95c-p5hm-xq8f","summary":"Overflow in netlink bytemsg length field allows attacker to override netlink-based container configuration in RunC","modified":"2026-09-10T03:49:10.478071172Z","packages":[{"ecosystem":"Go","name":"github.com/opencontainers/runc","purl":"pkg:golang/github.com/opencontainers/runc","ranges":["<1.0.3"],"fixed":["1.0.3"]}]},{"id":"GO-2022-0274","url":"https://osv.dev/vulnerability/GO-2022-0274","summary":"Namespace restriction bypass in github.com/opencontainers/runc","modified":"2026-02-04T02:26:28.343240Z","packages":[{"ecosystem":"Go","name":"github.com/opencontainers/runc","purl":"pkg:golang/github.com/opencontainers/runc","ranges":[">=1.0.1-0.20211012131345-9c444070ec7b <1.1.0"],"fixed":["1.1.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}