{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2021-47452",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-47452",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2024-05-22T06:19:42.721Z",
    "updatedAt": "2026-05-23T15:19:59.060Z",
    "importedAt": "2026-10-24T01:56:36.661Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "netfilter: nf_tables: skip netdev events generated on netns removal",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: skip netdev events generated on netns removal\n\nsyzbot reported following (harmless) WARN:\n\n WARNING: CPU: 1 PID: 2648 at net/netfilter/core.c:468\n  nft_netdev_unregister_hooks net/netfilter/nf_tables_api.c:230 [inline]\n  nf_tables_unregister_hook include/net/netfilter/nf_tables.h:1090 [inline]\n  __nft_release_basechain+0x138/0x640 net/netfilter/nf_tables_api.c:9524\n  nft_netdev_event net/netfilter/nft_chain_filter.c:351 [inline]\n  nf_tables_netdev_event+0x521/0x8a0 net/netfilter/nft_chain_filter.c:382\n\nreproducer:\nunshare -n bash -c 'ip link add br0 type bridge; nft add table netdev t ; \\\n nft add chain netdev t ingress \\{ type filter hook ingress device \"br0\" \\\n priority 0\\; policy drop\\; \\}'\n\nProblem is that when netns device exit hooks create the UNREGISTER\nevent, the .pre_exit hook for nf_tables core has already removed the\nbase hook.  Notifier attempts to do this again.\n\nThe need to do base hook unregister unconditionally was needed in the past,\nbecause notifier was last stage where reg->dev dereference was safe.\n\nNow that nf_tables does the hook removal in .pre_exit, this isn't\nneeded anymore.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "767d1216bff82507c945e92fe719dff2083bb2f4",
              "status": "affected",
              "versionType": "git",
              "lessThan": "90c7c58aa2bd02c65a4c63b7dfe0b16eab12cf9f"
            },
            {
              "version": "767d1216bff82507c945e92fe719dff2083bb2f4",
              "status": "affected",
              "versionType": "git",
              "lessThan": "68a3765c659f809dcaac20030853a054646eb739"
            },
            {
              "version": "b110391d1e806167254d3c7ae5d637191d913175",
              "status": "affected",
              "versionType": "git"
            },
            {
              "version": "0a0e5d47670b753d3dbf88f3c77a97a30864d9bd",
              "status": "affected",
              "versionType": "git"
            },
            {
              "version": "5.4.99",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "5.5"
            },
            {
              "version": "5.10.17",
              "status": "affected",
              "versionType": "semver",
              "lessThan": "5.11"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "5.11",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "5.11"
            },
            {
              "version": "5.14.15",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.14.*"
            },
            {
              "version": "5.15",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}