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Full vulnerability report · 2024
CVE-2021-46992High confidence

netfilter: nftables: avoid overflows in nft_hash_buckets()

Linux · Linux

7.8HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivelinux-raspi-realtimeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 8 Sept 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2021-33640

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

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

What

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

Why

The product reads data past the end, or before the beginning, of the intended buffer.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

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

Why

The product reads data past the end, or before the beginning, of the intended buffer.

How

An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
local access → Out-of-bounds Read → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-125

CWE-125: Out-of-bounds Read. The product reads data past the end, or before the beginning, of the intended buffer.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
CWE-125
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

CERT-FR · French · CERTFR-2024-AVI-0363Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2021-46971 Référence CVE CVE-2021-46976 https://www.cve.org/CVERecord?id=CVE-2021-46976 Référence CVE CVE-2021-46980 https://www.cve.org/CVERecord?id=CVE-2021-46980 Référence CVE CVE-2021-46981 https://www.cve.org/CVERecord?id=CVE-2021-46981 Référence CVE CVE-2021-46983 https://www.cve.org/CVERecord?id=CVE-2021-46983 Référence CVE CVE-2021-46984 https://www.cve.org/CVERecord?id=CVE-2021-46984 Référence CVE CVE-2021-46988 https://www.cve.org/CVERecord?id=CVE-2021-46988 Référence CVE CVE-2021-46990 https://www.cve.org/CVERecord?id=CVE-2021-46990 Référence CVE CVE-2021-46991 https://www.cve.org/CVERecord?id=CVE-2021-46991 Référence CVE CVE-2021-46992 https://www.cve.org/CVERecord?id=CVE-2021-46992 Référence CVE CVE-2021-46998 https://www.cve.org/CVERecord?id=CVE-2021-46998 Référence CVE CVE-2021-47000 https://www.cve.org/CVERecord?id=CVE-2021-47000 Référence CVE CVE-2021-47001 https://www.cve.org/CVERecord?id=CVE-2021-47001 Référence CVE CVE-2021-47003 https://www.cve.org/CVERecord?id=CVE-2021-47003 Référence CVE CVE-2021-47006 https://www.cve.org/CVERecord?id=CVE-2021-47006 Référence CVE CVE-2021-47009 https://www.cve.org/CVERecord?id=CVE-2021-47009 Référence CVE CVE-2021-47013 https://www.cve.org/CVERecord?id=CVE-2021-47013 Référence CVE CVE-2021-47014 https://www.cve.org/CVERecord?id=

Official advisory
CERT-FR · French · CERTFR-2024-AVI-0265Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2021-46929 Référence CVE CVE-2021-46932 https://www.cve.org/CVERecord?id=CVE-2021-46932 Référence CVE CVE-2021-46934 https://www.cve.org/CVERecord?id=CVE-2021-46934 Référence CVE CVE-2021-46953 https://www.cve.org/CVERecord?id=CVE-2021-46953 Référence CVE CVE-2021-46964 https://www.cve.org/CVERecord?id=CVE-2021-46964 Référence CVE CVE-2021-46966 https://www.cve.org/CVERecord?id=CVE-2021-46966 Référence CVE CVE-2021-46974 https://www.cve.org/CVERecord?id=CVE-2021-46974 Référence CVE CVE-2021-46989 https://www.cve.org/CVERecord?id=CVE-2021-46989 Référence CVE CVE-2021-46991 https://www.cve.org/CVERecord?id=CVE-2021-46991 Référence CVE CVE-2021-46992 https://www.cve.org/CVERecord?id=CVE-2021-46992 Référence CVE CVE-2021-47005 https://www.cve.org/CVERecord?id=CVE-2021-47005 Référence CVE CVE-2021-47012 https://www.cve.org/CVERecord?id=CVE-2021-47012 Référence CVE CVE-2021-47013 https://www.cve.org/CVERecord?id=CVE-2021-47013 Référence CVE CVE-2021-47054 https://www.cve.org/CVERecord?id=CVE-2021-47054 Référence CVE CVE-2021-47060 https://www.cve.org/CVERecord?id=CVE-2021-47060 Référence CVE CVE-2021-47061 https://www.cve.org/CVERecord?id=CVE-2021-47061 Référence CVE CVE-2021-47069 https://www.cve.org/CVERecord?id=CVE-2021-47069 Référence CVE CVE-2021-47076 https://www.cve.org/CVERecord?id=

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
0ed6389c483dc77cdbdd48de0ca7ce41723dd667 < 2824cafc6a93792d9ad85939c499161214d84c4b; 0ed6389c483dc77cdbdd48de0ca7ce41723dd667 < efcd730ddd6f25578bd31bfe703e593e2421d708; 0ed6389c483dc77cdbdd48de0ca7ce41723dd667 < c77e2ef18167ad334e27610ced9a7f6af5ec1787; 0ed6389c483dc77cdbdd48de0ca7ce41723dd667 < 72b49dd116ca00a46a11d5a4d8d7987f05ed9cd7; 0ed6389c483dc77cdbdd48de0ca7ce41723dd667 < 1e8ab479cfbe5751efccedb95afb9b112a5ba475; 0ed6389c483dc77cdbdd48de0ca7ce41723dd667 < a388d10961ff8578b1a6691945d406c0f33aa71b; 0ed6389c483dc77cdbdd48de0ca7ce41723dd667 < a54754ec9891830ba548e2010c889e3c8146e449; 4.9
Fixed
< 4.9; 4.14.233 ≤ 4.14.*; 4.19.191 ≤ 4.19.*; 5.4.120 ≤ 5.4.*; 5.10.38 ≤ 5.10.*; 5.11.22 ≤ 5.11.*; 5.12.5 ≤ 5.12.*; 5.13 ≤ *
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 28 Feb 2024 · Last source change 5 Aug 2026, 08:45 UTC · CWE-125 · Out-of-bounds Read

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2021-33640
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2021-46992 · cve.blacktree.nl