---
id: CVE-2021-46913
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nftables: clone set element expression template

  memcpy() breaks when using connlimit in set elements
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nftables: clone set element expression template

  memcpy() breaks when using connlimit in set elements. Use
  nft_expr_clone() to initialize the connlimit expre…
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'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.7.0, < 5.10.64'
  - 'linux_kernel >= 5.11.0, < 5.11.16'
patched:
  - linux_kernel 5.11.16
published: '2024-02-27'
updated: '2026-08-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-46913'
references:
  - url: 'https://git.kernel.org/stable/c/47d8de3c226574a3ddb8b87d0c152028d1bafef4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4d8f9065830e526c83199186c5f56a6514f457d2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e51ff3ffc316377cca21de8b80404eed0c37b3c3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/47d8de3c226574a3ddb8b87d0c152028d1bafef4'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/4d8f9065830e526c83199186c5f56a6514f457d2'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://git.kernel.org/stable/c/e51ff3ffc316377cca21de8b80404eed0c37b3c3'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.00241
epssPercentile: 0.13658
ingestedAt: '2026-08-04T10:39:38.253Z'
---

## Overview

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

netfilter: nftables: clone set element expression template

memcpy() breaks when using connlimit in set elements. Use
nft_expr_clone() to initialize the connlimit expression list, otherwise
connlimit garbage collector crashes when walking on the list head copy.

[  493.064656] Workqueue: events_power_efficient nft_rhash_gc [nf_tables]
[  493.064685] RIP: 0010:find_or_evict+0x5a/0x90 [nf_conncount]
[  493.064694] Code: 2b 43 40 83 f8 01 77 0d 48 c7 c0 f5 ff ff ff 44 39 63 3c 75 df 83 6d 18 01 48 8b 43 08 48 89 de 48 8b 13 48 8b 3d ee 2f 00 00 <48> 89 42 08 48 89 10 48 b8 00 01 00 00 00 00 ad de 48 89 03 48 83
[  493.064699] RSP: 0018:ffffc90000417dc0 EFLAGS: 00010297
[  493.064704] RAX: 0000000000000000 RBX: ffff888134f38410 RCX: 0000000000000000
[  493.064708] RDX: 0000000000000000 RSI: ffff888134f38410 RDI: ffff888100060cc0
[  493.064711] RBP: ffff88812ce594a8 R08: ffff888134f38438 R09: 00000000ebb9025c
[  493.064714] R10: ffffffff8219f838 R11: 0000000000000017 R12: 0000000000000001
[  493.064718] R13: ffffffff82146740 R14: ffff888134f38410 R15: 0000000000000000
[  493.064721] FS:  0000000000000000(0000) GS:ffff88840e440000(0000) knlGS:0000000000000000
[  493.064725] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  493.064729] CR2: 0000000000000008 CR3: 00000001330aa002 CR4: 00000000001706e0
[  493.064733] Call Trace:
[  493.064737]  nf_conncount_gc_list+0x8f/0x150 [nf_conncount]
[  493.064746]  nft_rhash_gc+0x106/0x390 [nf_tables]

## Affected

- `linux_kernel >= 5.7.0, < 5.10.64`
- `linux_kernel >= 5.11.0, < 5.11.16`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.11.16`