{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47247", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-04-10T18:59:19.534Z", "datePublished": "2024-05-21T14:19:44.947Z", "dateUpdated": "2026-08-05T08:46:57.490Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:46:57.490Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Fix use-after-free of encap entry in neigh update handler\n\nFunction mlx5e_rep_neigh_update() wasn't updated to accommodate rtnl lock\nremoval from TC filter update path and properly handle concurrent encap\nentry insertion/deletion which can lead to following use-after-free:\n\n [23827.464923] ==================================================================\n [23827.469446] BUG: KASAN: use-after-free in mlx5e_encap_take+0x72/0x140 [mlx5_core]\n [23827.470971] Read of size 4 at addr ffff8881d132228c by task kworker/u20:6/21635\n [23827.472251]\n [23827.472615] CPU: 9 PID: 21635 Comm: kworker/u20:6 Not tainted 5.13.0-rc3+ #5\n [23827.473788] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014\n [23827.475639] Workqueue: mlx5e mlx5e_rep_neigh_update [mlx5_core]\n [23827.476731] Call Trace:\n [23827.477260] dump_stack+0xbb/0x107\n [23827.477906] print_address_description.constprop.0+0x18/0x140\n [23827.478896] ? mlx5e_encap_take+0x72/0x140 [mlx5_core]\n [23827.479879] ? mlx5e_encap_take+0x72/0x140 [mlx5_core]\n [23827.480905] kasan_report.cold+0x7c/0xd8\n [23827.481701] ? mlx5e_encap_take+0x72/0x140 [mlx5_core]\n [23827.482744] kasan_check_range+0x145/0x1a0\n [23827.493112] mlx5e_encap_take+0x72/0x140 [mlx5_core]\n [23827.494054] ? mlx5e_tc_tun_encap_info_equal_generic+0x140/0x140 [mlx5_core]\n [23827.495296] mlx5e_rep_neigh_update+0x41e/0x5e0 [mlx5_core]\n [23827.496338] ? mlx5e_rep_neigh_entry_release+0xb80/0xb80 [mlx5_core]\n [23827.497486] ? read_word_at_a_time+0xe/0x20\n [23827.498250] ? strscpy+0xa0/0x2a0\n [23827.498889] process_one_work+0x8ac/0x14e0\n [23827.499638] ? lockdep_hardirqs_on_prepare+0x400/0x400\n [23827.500537] ? pwq_dec_nr_in_flight+0x2c0/0x2c0\n [23827.501359] ? rwlock_bug.part.0+0x90/0x90\n [23827.502116] worker_thread+0x53b/0x1220\n [23827.502831] ? process_one_work+0x14e0/0x14e0\n [23827.503627] kthread+0x328/0x3f0\n [23827.504254] ? _raw_spin_unlock_irq+0x24/0x40\n [23827.505065] ? __kthread_bind_mask+0x90/0x90\n [23827.505912] ret_from_fork+0x1f/0x30\n [23827.506621]\n [23827.506987] Allocated by task 28248:\n [23827.507694] kasan_save_stack+0x1b/0x40\n [23827.508476] __kasan_kmalloc+0x7c/0x90\n [23827.509197] mlx5e_attach_encap+0xde1/0x1d40 [mlx5_core]\n [23827.510194] mlx5e_tc_add_fdb_flow+0x397/0xc40 [mlx5_core]\n [23827.511218] __mlx5e_add_fdb_flow+0x519/0xb30 [mlx5_core]\n [23827.512234] mlx5e_configure_flower+0x191c/0x4870 [mlx5_core]\n [23827.513298] tc_setup_cb_add+0x1d5/0x420\n [23827.514023] fl_hw_replace_filter+0x382/0x6a0 [cls_flower]\n [23827.514975] fl_change+0x2ceb/0x4a51 [cls_flower]\n [23827.515821] tc_new_tfilter+0x89a/0x2070\n [23827.516548] rtnetlink_rcv_msg+0x644/0x8c0\n [23827.517300] netlink_rcv_skb+0x11d/0x340\n [23827.518021] netlink_unicast+0x42b/0x700\n [23827.518742] netlink_sendmsg+0x743/0xc20\n [23827.519467] sock_sendmsg+0xb2/0xe0\n [23827.520131] ____sys_sendmsg+0x590/0x770\n [23827.520851] ___sys_sendmsg+0xd8/0x160\n [23827.521552] __sys_sendmsg+0xb7/0x140\n [23827.522238] do_syscall_64+0x3a/0x70\n [23827.522907] entry_SYSCALL_64_after_hwframe+0x44/0xae\n [23827.523797]\n [23827.524163] Freed by task 25948:\n [23827.524780] kasan_save_stack+0x1b/0x40\n [23827.525488] kasan_set_track+0x1c/0x30\n [23827.526187] kasan_set_free_info+0x20/0x30\n [23827.526968] __kasan_slab_free+0xed/0x130\n [23827.527709] slab_free_freelist_hook+0xcf/0x1d0\n [23827.528528] kmem_cache_free_bulk+0x33a/0x6e0\n [23827.529317] kfree_rcu_work+0x55f/0xb70\n [23827.530024] process_one_work+0x8ac/0x14e0\n [23827.530770] worker_thread+0x53b/0x1220\n [23827.531480] kthread+0x328/0x3f0\n [23827.532114] ret_from_fork+0x1f/0x30\n [23827.532785]\n [23827.533147] Last potentially related work creation:\n [23827.534007] kasan_save_stack+0x1b/0x40\n [23827.534710] kasan_record_aux_stack+0xab/0xc0\n [23827.535492] kvfree_call_rcu+0x31/0x7b0\n [23827.536206] mlx5e_tc_del\n---truncated---" } ], "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 UAF is reached via local rtnetlink TC flower add/delete (tc_new_tfilter/tc_del_tfilter → mlx5e_configure_flower/mlx5e_delete_flower → encap attach/detach) racing with the mlx5e neigh-update workqueue, not by unauthenticated remote packet processing.\nAC:L - An attacker with TC access fully controls both sides of the race by concurrently installing/deleting tunnel-encap FDB flower rules while driving NETEVENT_NEIGH_UPDATE (ARP/ND or neigh updates), so success does not depend on conditions outside attacker influence.\nPR:L - Creating and deleting the offloaded TC flower filters requires CAP_NET_ADMIN via netlink_ns_capable() in the netns user_ns, which is obtainable through user namespaces and matches prior mlx5e FDB TC scoring (e.g. CVE-2022-49025, CVE-2023-52487).\nUI:N - The attacker installs and deletes the encap TC rules and triggers neighbour updates themselves; no separate victim action is required beyond the host already running mlx5 switchdev offloads.\nS:U - The encap-entry heap UAF corrupts memory inside the host kernel’s mlx5 eswitch offload authority and does not cross a VM, IOMMU, or other security-authority boundary.\nC:H - KASAN documents a slab use-after-free of mlx5e_encap_entry (kmalloc-256) in mlx5e_encap_take(); reclaim of the freed object enables arbitrary kernel memory disclosure under standard UAF exploitation.\nI:H - The same heap UAF of the encap entry during concurrent list walk/take allows heap spray and corruption of reclaimed objects, yielding write and control-flow hijack primitives consistent with other kernel UAFs.\nA:H - Any use-after-free is high availability impact; the reported path oopses in mlx5e_rep_neigh_update → mlx5e_encap_take even when not fully exploited for code execution." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/mellanox/mlx5/core/en/rep/neigh.c", "drivers/net/ethernet/mellanox/mlx5/core/en/rep/tc.c", "drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun_encap.c", "drivers/net/ethernet/mellanox/mlx5/core/en_tc.h" ], "versions": [ { "version": "2a1f1768fa17805ca2e937e2e034a7c3433d3bdc", "lessThan": "0d1e7a7964ce6abb28883a3906bbc20fe0009f03", "status": "affected", "versionType": "git" }, { "version": "2a1f1768fa17805ca2e937e2e034a7c3433d3bdc", "lessThan": "b6447b72aca571632e71bb73a797118d5ce46a93", "status": "affected", "versionType": "git" }, { "version": "2a1f1768fa17805ca2e937e2e034a7c3433d3bdc", "lessThan": "fb1a3132ee1ac968316e45d21a48703a6db0b6c3", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/mellanox/mlx5/core/en/rep/neigh.c", "drivers/net/ethernet/mellanox/mlx5/core/en/rep/tc.c", "drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun_encap.c", "drivers/net/ethernet/mellanox/mlx5/core/en_tc.h" ], "versions": [ { "version": "5.4", "status": "affected" }, { "version": "0", "lessThan": "5.4", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.237", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.12.13", "lessThanOrEqual": "5.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.13", "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": "5.4", "versionEndExcluding": "5.10.237" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "5.12.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "5.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0d1e7a7964ce6abb28883a3906bbc20fe0009f03" }, { "url": "https://git.kernel.org/stable/c/b6447b72aca571632e71bb73a797118d5ce46a93" }, { "url": "https://git.kernel.org/stable/c/fb1a3132ee1ac968316e45d21a48703a6db0b6c3" } ], "title": "net/mlx5e: Fix use-after-free of encap entry in neigh update handler", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CISA ADP Vulnrichment", "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47247", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-05-28T15:53:08.543525Z" } } } ], "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:15:17.168Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/b6447b72aca571632e71bb73a797118d5ce46a93", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/fb1a3132ee1ac968316e45d21a48703a6db0b6c3", "tags": [ "x_transferred" ] }, { "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:26:38.429Z" } } ] } }