{"id":"CVE-2021-21284","details":"In Docker before versions 9.03.15, 20.10.3 there is a vulnerability involving the --userns-remap option in which access to remapped root allows privilege escalation to real root. When using \"--userns-remap\", if the root user in the remapped namespace has access to the host filesystem they can modify files under \"/var/lib/docker/\u003cremapping\u003e\" that cause writing files with extended privileges. Versions 20.10.3 and 19.03.15 contain patches that prevent privilege escalation from remapped user.","aliases":["GHSA-7452-xqpj-6rpc"],"modified":"2026-04-10T04:29:35.279278Z","published":"2021-02-02T18:15:11.827Z","related":["CGA-pv2f-w2w8-cmqj","GHSA-7452-xqpj-6rpc","SUSE-SU-2021:0435-1","SUSE-SU-2021:0445-1","SUSE-SU-2021:1458-1","SUSE-SU-2021:1954-1","SUSE-SU-2025:03540-1","SUSE-SU-2025:03545-1","openSUSE-SU-2021:0278-1","openSUSE-SU-2021:0878-1","openSUSE-SU-2021:1954-1","openSUSE-SU-2024:10722-1","openSUSE-SU-2025:15589-1"],"references":[{"type":"ADVISORY","url":"https://www.debian.org/security/2021/dsa-4865"},{"type":"ADVISORY","url":"https://docs.docker.com/engine/release-notes/#20103"},{"type":"ADVISORY","url":"https://github.com/moby/moby/releases/tag/v19.03.15"},{"type":"ADVISORY","url":"https://github.com/moby/moby/releases/tag/v20.10.3"},{"type":"ADVISORY","url":"https://github.com/moby/moby/security/advisories/GHSA-7452-xqpj-6rpc"},{"type":"ADVISORY","url":"https://security.netapp.com/advisory/ntap-20210226-0005/"},{"type":"FIX","url":"https://github.com/moby/moby/commit/64bd4485b3a66a597c02c95f5776395e540b2c7c"},{"type":"FIX","url":"https://security.gentoo.org/glsa/202107-23"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/docker/docker","events":[{"introduced":"0"},{"fixed":"420b1d36250f9cfdc561f086f25a213ecb669b6f"},{"introduced":"0"},{"fixed":"46229ca1d815cfd4b50eb377ac75ad8300e13a85"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"19.03.15"},{"introduced":"20.0.0"},{"fixed":"20.10.3"}]}},{"type":"GIT","repo":"https://github.com/moby/moby","events":[{"introduced":"0"},{"fixed":"64bd4485b3a66a597c02c95f5776395e540b2c7c"},{"fixed":"420b1d36250f9cfdc561f086f25a213ecb669b6f"},{"fixed":"46229ca1d815cfd4b50eb377ac75ad8300e13a85"}]}],"versions":["0.0.3","docs-v1.12.0-rc4-2016-07-15","upstream/0.1.2","upstream/0.1.3","v0.1.0","v0.1.1","v0.1.2","v0.1.3","v0.1.4","v0.1.5","v0.1.6","v0.1.7","v0.1.8","v0.2.0","v0.2.1","v0.2.2","v0.3.0","v0.3.1","v0.3.2","v0.4.1","v0.4.2","v0.4.4","v0.4.5","v0.4.7","v0.5.0","v0.6.5","v0.7.0","v0.7.1","v0.7.2","v18.06.0-ce-rc1","v18.09.0-ce-tp0","v19.03.0","v19.03.0-beta1","v19.03.0-beta2","v19.03.0-beta3","v19.03.0-beta4","v19.03.0-beta5","v19.03.0-rc2","v19.03.0-rc3","v19.03.1","v19.03.10","v19.03.11","v19.03.12","v19.03.13","v19.03.13-beta1","v19.03.13-beta2","v19.03.14","v19.03.2","v19.03.2-beta1","v19.03.2-rc1","v19.03.3","v19.03.3-beta1","v19.03.3-beta2","v19.03.3-rc1","v19.03.4","v19.03.4-rc1","v19.03.5","v19.03.5-beta1","v19.03.5-beta2","v19.03.5-rc1","v19.03.6","v19.03.6-rc1","v19.03.6-rc2","v19.03.7","v19.03.8","v19.03.9","v20.10.0","v20.10.0-beta1","v20.10.0-rc1","v20.10.0-rc2","v20.10.1","v20.10.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-21284.json","unresolved_ranges":[{"events":[{"introduced":"0"},{"last_affected":"10.0"}]},{"events":[{"introduced":"11.0.0"},{"last_affected":"11.60.3"}]}]}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N"}]}