{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47517", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-05-24T15:02:54.824Z", "datePublished": "2024-05-24T15:09:30.675Z", "dateUpdated": "2026-08-05T08:48:13.450Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:48:13.450Z" }, "descriptions": [ { "lang": "en", "value": "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" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is triggered via the ethtool Generic Netlink interface (AF_NETLINK / ETHTOOL_MSG_*_SET), a local syscall path; the ioctl path is unaffected and there is no remote packet-processing entry.\nAC:L - An attacker who can create and delete a netdev (e.g. veth) and issue ethtool CHANNELS_SET controls both sides of the race: hold a ref via ethnl_parse_header_dev_get, unregister under rtnl (tearing down queue kobjects), then set channels after rtnl is free—winning the window is attacker-driven and retryable.\nPR:L - CHANNELS_SET (and other SET ops that call ethnl_ops_begin) require GENL_UNS_ADMIN_PERM, i.e. CAP_NET_ADMIN in the network namespace’s user_ns; with netnsok and unshare -Urn this is available to an unprivileged userns user, not real init-ns root.\nUI:N - The attacker creates the device, races unregister with ethtool SET, and triggers the UAF themselves; no separate victim action is required.\nS:U - Impact is kernel heap UAF / oops within the same host OS authority (ethtool/netdevice sysfs kobjects); this is not a VM escape, IOMMU bypass, or other cross-boundary compromise.\nC:H - The fix documents a KASAN use-after-free in kobject_get when adding Tx queues after unregister; per guidance a UAF yields a high confidentiality impact via heap reuse/read primitives.\nI:H - The same UAF on unregistered queues_kset/queue kobjects enables heap spray and corruption of adjacent objects, supporting write and control-flow hijacking primitives.\nA:H - The report shows KASAN UAF and NULL pointer exceptions from operating on unregistering devices, which can oops/panic the kernel and fully impact availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ethtool/netlink.c" ], "versions": [ { "version": "041b1c5d4a53e97fc9e029ae32469552ca12cb9b", "lessThan": "7c26da3be1e9843a15b5318f90db8a564479d2ac", "status": "affected", "versionType": "git" }, { "version": "041b1c5d4a53e97fc9e029ae32469552ca12cb9b", "lessThan": "cfd719f04267108f5f5bf802b9d7de69e99a99f9", "status": "affected", "versionType": "git" }, { "version": "041b1c5d4a53e97fc9e029ae32469552ca12cb9b", "lessThan": "dde91ccfa25fd58f64c397d91b81a4b393100ffa", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ethtool/netlink.c" ], "versions": [ { "version": "5.6", "status": "affected" }, { "version": "0", "lessThan": "5.6", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.87", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.8", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.10.87" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.15.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/7c26da3be1e9843a15b5318f90db8a564479d2ac" }, { "url": "https://git.kernel.org/stable/c/cfd719f04267108f5f5bf802b9d7de69e99a99f9" }, { "url": "https://git.kernel.org/stable/c/dde91ccfa25fd58f64c397d91b81a4b393100ffa" } ], "title": "ethtool: do not perform operations on net devices being unregistered", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CISA ADP Vulnrichment", "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47517", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-05-24T19:18:28.551288Z" } } } ], "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:13:57.373Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:39:59.610Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/7c26da3be1e9843a15b5318f90db8a564479d2ac", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/cfd719f04267108f5f5bf802b9d7de69e99a99f9", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/dde91ccfa25fd58f64c397d91b81a4b393100ffa", "tags": [ "x_transferred" ] } ] } ] } }