---
id: CVE-2021-46992
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nftables: avoid overflows in nft_hash_buckets()

  Number of buckets being stored in 32bit variables, we have to
  ensure that no overflows occur in nft_hash_buc…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nftables: avoid overflows in nft_hash_buckets()

  Number of buckets being stored in 32bit variables, we have to
  ensure that no overflows occur in nft_hash_buc…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-125
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 4.9, < 4.14.233'
  - 'linux_kernel >= 4.15, < 4.19.191'
  - 'linux_kernel >= 4.20, < 5.4.120'
  - 'linux_kernel >= 5.5, < 5.10.38'
  - 'linux_kernel >= 5.11, < 5.11.22'
  - 'linux_kernel >= 5.12, < 5.12.5'
patched:
  - linux_kernel 5.12.5
published: '2024-02-28'
updated: '2026-08-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-46992'
references:
  - url: 'https://git.kernel.org/stable/c/1e8ab479cfbe5751efccedb95afb9b112a5ba475'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2824cafc6a93792d9ad85939c499161214d84c4b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/72b49dd116ca00a46a11d5a4d8d7987f05ed9cd7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a388d10961ff8578b1a6691945d406c0f33aa71b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a54754ec9891830ba548e2010c889e3c8146e449'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c77e2ef18167ad334e27610ced9a7f6af5ec1787'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/efcd730ddd6f25578bd31bfe703e593e2421d708'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/1e8ab479cfbe5751efccedb95afb9b112a5ba475'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/2824cafc6a93792d9ad85939c499161214d84c4b'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/72b49dd116ca00a46a11d5a4d8d7987f05ed9cd7'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/a388d10961ff8578b1a6691945d406c0f33aa71b'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/a54754ec9891830ba548e2010c889e3c8146e449'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/c77e2ef18167ad334e27610ced9a7f6af5ec1787'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/efcd730ddd6f25578bd31bfe703e593e2421d708'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00261
epssPercentile: 0.15851
ingestedAt: '2026-08-04T10:39:38.911Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nftables: avoid overflows in nft_hash_buckets()

Number of buckets being stored in 32bit variables, we have to
ensure that no overflows occur in nft_hash_buckets()

syzbot injected a size == 0x40000000 and reported:

UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
shift exponent 64 is too large for 64-bit type 'long unsigned int'
CPU: 1 PID: 29539 Comm: syz-executor.4 Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327
 __roundup_pow_of_two include/linux/log2.h:57 [inline]
 nft_hash_buckets net/netfilter/nft_set_hash.c:411 [inline]
 nft_hash_estimate.cold+0x19/0x1e net/netfilter/nft_set_hash.c:652
 nft_select_set_ops net/netfilter/nf_tables_api.c:3586 [inline]
 nf_tables_newset+0xe62/0x3110 net/netfilter/nf_tables_api.c:4322
 nfnetlink_rcv_batch+0xa09/0x24b0 net/netfilter/nfnetlink.c:488
 nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:612 [inline]
 nfnetlink_rcv+0x3af/0x420 net/netfilter/nfnetlink.c:630
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:674
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46

## Affected

- `linux_kernel >= 4.9, < 4.14.233`
- `linux_kernel >= 4.15, < 4.19.191`
- `linux_kernel >= 4.20, < 5.4.120`
- `linux_kernel >= 5.5, < 5.10.38`
- `linux_kernel >= 5.11, < 5.11.22`
- `linux_kernel >= 5.12, < 5.12.5`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.12.5`