{"id":"CVE-2021-47010","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: Only allow init netns to set default tcp cong to a restricted algo\n\ntcp_set_default_congestion_control() is netns-safe in that it writes\nto &net-\u003eipv4.tcp_congestion_control, but it also sets\nca-\u003eflags |= TCP_CONG_NON_RESTRICTED which is not namespaced.\nThis has the unintended side-effect of changing the global\nnet.ipv4.tcp_allowed_congestion_control sysctl, despite the fact that it\nis read-only: 97684f0970f6 (\"net: Make tcp_allowed_congestion_control\nreadonly in non-init netns\")\n\nResolve this netns \"leak\" by only allowing the init netns to set the\ndefault algorithm to one that is restricted. This restriction could be\nremoved if tcp_allowed_congestion_control were namespace-ified in the\nfuture.\n\nThis bug was uncovered with\nhttps://github.com/JonathonReinhart/linux-netns-sysctl-verify","modified":"2026-03-15T22:42:44.319865Z","published":"2024-02-28T09:15:38.657Z","references":[{"type":"FIX","url":"https://git.kernel.org/stable/c/efe1532a6e1a8e3c343d04fff510f0ed80328f9c"},{"type":"FIX","url":"https://git.kernel.org/stable/c/6c1ea8bee75df8fe2184a50fcd0f70bf82986f42"},{"type":"FIX","url":"https://git.kernel.org/stable/c/8d432592f30fcc34ef5a10aac4887b4897884493"},{"type":"FIX","url":"https://git.kernel.org/stable/c/9884f745108f7d25b189bbcd6754e284fb29ab68"},{"type":"FIX","url":"https://git.kernel.org/stable/c/992de06308d9a9584d59b96d294ac676f924e437"},{"type":"FIX","url":"https://git.kernel.org/stable/c/e7d7bedd507bb732e600403b7a96f9fe48d0ca31"}],"affected":[{"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"4.15"},{"fixed":"4.19.191"}]},{"events":[{"introduced":"4.20"},{"fixed":"5.4.119"}]},{"events":[{"introduced":"5.5"},{"fixed":"5.10.37"}]},{"events":[{"introduced":"5.11"},{"fixed":"5.11.21"}]},{"events":[{"introduced":"5.12"},{"fixed":"5.12.4"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47010.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}