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TI-2021-21769 Aliases CVE-2021-47106GHSA-gmwj-428v-53wv

netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy()

Priority LOW 33CWE-416Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy() We need to use list_for_each_entry_safe() iterator because we can not access @catchall after kfree_rcu() call. syzbot reported: BUG: KASAN: use-after-free in nft_set_catchall_destroy net/netfilter/nf_tables_api.c:4486 [inline] BUG: KASAN: use-after-free in nft_set_destroy net/netfilter/nf_tables_api.c:4504 [inline] BUG: KASAN: use-after-free in nft_set_destroy+0x3fd/0x4f0 net/netfilter/nf_tables_api.c:4493 Read of size 8 at addr ffff8880716e5b80 by task syz-executor.3/8871 CPU: 1 PID: 8871 Comm: syz-executor.3 Not tainted 5.16.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x2ed mm/kasan/report.c:247 __kasan_report mm/kasan/report.c:433 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:450 nft_set_catchall_destroy net/netfilter/nf_tables_api.c:4486 [inline] nft_set_destroy net/netfilter/nf_tables_api.c:4504 [inline] nft_set_destroy+0x3fd/0x4f0 net/netfilter/nf_tables_api.c:4493 __nft_release_table+0x79f/0xcd0 net/netfilter/nf_tables_api.c:9626 nft_rcv_nl_event+0x4f8/0x670 net/netfilter/nf_tables_api.c:9688 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83 blocking_notifier_call_chain kernel/notifier.c:318 [inline] blocking_notifier_call_chain+0x67/0x90 kernel/notifier.c:306 netlink_release+0xcb6/0x1dd0 net/netlink/af_netlink.c:788 __sock_release+0xcd/0x280 net/socket.c:649 sock_close+0x18/0x20 net/socket.c:1314 __fput+0x286/0x9f0 fs/file_table.c:280 task_work_run+0xdd/0x1a0 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f75fbf28adb Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44 RSP: 002b:00007ffd8da7ec10 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007f75fbf28adb RDX: 00007f75fc08e828 RSI: ffffffffffffffff RDI: 0000000000000003 RBP: 00007f75fc08a960 R08: 0000000000000000 R09: 00007f75fc08e830 R10: 00007ffd8da7ed10 R11: 0000000000000293 R12: 00000000002067c3 R13: 00007ffd8da7ed10 R14: 00007f75fc088f60 R15: 0000000000000032 </TASK> Allocated by task 8886: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0xa6/0xd0 mm/kasan/common.c:522 kasan_kmalloc include/linux/kasan.h:269 [inline] kmem_cache_alloc_trace+0x1ea/0x4a0 mm/slab.c:3575 kmalloc include/linux/slab.h:590 [inline] nft_setelem_catchall_insert net/netfilter/nf_tables_api.c:5544 [inline] nft_setelem_insert net/netfilter/nf_tables_api.c:5562 [inline] nft_add_set_elem+0x232e/0x2f40 net/netfilter/nf_tables_api.c:5936 nf_tables_newsetelem+0x6ff/0xbb0 net/netfilter/nf_tables_api.c:6032 nfnetlink_rcv_batch+0x1710/0x25f0 net/netfilter/nfnetlink.c:513 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:634 [inline] nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:652 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x904/0xdf0 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/ ---truncated---

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00218 12th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.15.12, 5.16Red Hat: 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux5.13 and later5.15.12, 5.16Patch availableCNA
  • Linux VendorLinux Affected 5.13 and later Fixed in 5.15.12, 5.16 Patch available CNA

CPE configurations NVD · 7

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*5.13 to before 5.15.12VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*5.16 rc1VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:*5.16 rc2VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:*5.16 rc3VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:*5.16 rc4VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.16:rc5:*:*:*:*:*:*5.16 rc5VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.16:rc6:*:*:*:*:*:*5.16 rc6VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.13 to before 5.15.12 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:* Versions 5.16 rc1 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:* Versions 5.16 rc2 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:* Versions 5.16 rc3 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:* Versions 5.16 rc4 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.16:rc5:*:*:*:*:*:* Versions 5.16 rc5 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.16:rc6:*:*:*:*:*:* Versions 5.16 rc6 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 5.15.12, 5.16

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 8AffectedNo fix planned: Will not fix
Not affected: 3 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-47106
  2. 2026-10-03 Alias added: GHSA-gmwj-428v-53wv

References

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources