5.5

CVE-2021-47452: netfilter: nf_tables: skip netdev events generated on netns removal

Analyzed
AliasesUBUNTU-CVE-2021-47452DEBIAN-CVE-2021-47452
Published 22-05-2024Last modified 23-05-2026

Vulnerability summary

CVE-2021-47452 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 9.4% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.20%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 5 · Related 5
SUSE-SU-2024:2008-1SUSE-SU-2024:2011-1SUSE-SU-2024:2019-1SUSE-SU-2024:2189-1SUSE-SU-2024:2190-1

Timeline

  1. 22-05-2024
    PublishedVulnerability first disclosed.
  2. 23-05-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: skip netdev events generated on netns removal syzbot reported following (harmless) WARN: WARNING: CPU: 1 PID: 2648 at net/netfilter/core.c:468 nft_netdev_unregister_hooks net/netfilter/nf_tables_api.c:230 [inline] nf_tables_unregister_hook include/net/netfilter/nf_tables.h:1090 [inline] __nft_release_basechain+0x138/0x640 net/netfilter/nf_tables_api.c:9524 nft_netdev_event net/netfilter/nft_chain_filter.c:351 [inline] nf_tables_netdev_event+0x521/0x8a0 net/netfilter/nft_chain_filter.c:382 reproducer: unshare -n bash -c 'ip link add br0 type bridge; nft add table netdev t ; \ nft add chain netdev t ingress \{ type filter hook ingress device "br0" \ priority 0\; policy drop\; \}' Problem is that when netns device exit hooks create the UNREGISTER event, the .pre_exit hook for nf_tables core has already removed the base hook. Notifier attempts to do this again. The need to do base hook unregister unconditionally was needed in the past, because notifier was last stage where reg->dev dereference was safe. Now that nf_tables does the hook removal in .pre_exit, this isn't needed anymore.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.20%

Chance of exploitation in the next 30 days

Percentile

9%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.20% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu86 products
  • linuxAll versions (No fix recorded)
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded)
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 767d1216bff82507c945e92fe719dff2083bb2f4, < 90c7c58aa2bd02c65a4c63b7dfe0b16eab12cf9f | ≥ 767d1216bff82507c945e92fe719dff2083bb2f4, < 68a3765c659f809dcaac20030853a054646eb739 | b110391d1e806167254d3c7ae5d637191d913175 | 0a0e5d47670b753d3dbf88f3c77a97a30864d9bd | ≥ 5.4.99, < 5.5 | ≥ 5.10.17, < 5.11 | 5.11
  • linux_kernelEOL≥ 5.4.99, < 5.5 | ≥ 5.10.17, < 5.11 | ≥ 5.11.1, < 5.14.15 | 5.11 | 5.15:rc1 | 5.15:rc2 | 5.15:rc3 | 5.15:rc4 | 5.15:rc5 | 5.15:rc6
Debian1 product
  • linux< 5.14.16-1

3 vendors · 89 products

References

6 links