{"cve":"CVE-2021-47517","nvd":{"published":"2024-05-24T15:15:13.347","modified":"2026-08-04T10:17:07.130","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nethtool: do not perform operations on net devices being unregistered\n\nThere is a short period between a net device starts to be unregistered\nand when it is actually gone. In that time frame ethtool operations\ncould still be performed, which might end up in unwanted or undefined\nbehaviours[1].\n\nDo not allow ethtool operations after a net device starts its\nunregistration. This patch targets the netlink part as the ioctl one\nisn't affected: the reference to the net device is taken and the\noperation is executed within an rtnl lock section and the net device\nwon't be found after unregister.\n\n[1] For example adding Tx queues after unregister ends up in NULL\n    pointer exceptions and UaFs, such as:\n\n      BUG: KASAN: use-after-free in kobject_get+0x14/0x90\n      Read of size 1 at addr ffff88801961248c by task ethtool/755\n\n      CPU: 0 PID: 755 Comm: ethtool Not tainted 5.15.0-rc6+ #778\n      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/014\n      Call Trace:\n       dump_stack_lvl+0x57/0x72\n       print_address_description.constprop.0+0x1f/0x140\n       kasan_report.cold+0x7f/0x11b\n       kobject_get+0x14/0x90\n       kobject_add_internal+0x3d1/0x450\n       kobject_init_and_add+0xba/0xf0\n       netdev_queue_update_kobjects+0xcf/0x200\n       netif_set_real_num_tx_queues+0xb4/0x310\n       veth_set_channels+0x1c3/0x550\n       ethnl_set_channels+0x524/0x610","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-416"],"references":["https://git.kernel.org/stable/c/7c26da3be1e9843a15b5318f90db8a564479d2ac","https://git.kernel.org/stable/c/cfd719f04267108f5f5bf802b9d7de69e99a99f9","https://git.kernel.org/stable/c/dde91ccfa25fd58f64c397d91b81a4b393100ffa","https://git.kernel.org/stable/c/7c26da3be1e9843a15b5318f90db8a564479d2ac","https://git.kernel.org/stable/c/cfd719f04267108f5f5bf802b9d7de69e99a99f9"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2021-47517","score":0.00246,"percentile":0.15947,"date":"2026-10-31"},"kev":null,"osv":[],"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."]}