{
  "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-2026-31421",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-31421",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-04-13T13:40:25.278Z",
    "updatedAt": "2026-10-15T01:16:00.824Z",
    "importedAt": "2026-10-24T01:58:02.025Z",
    "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": "net/sched: cls_fw: fix NULL pointer dereference on shared blocks",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_fw: fix NULL pointer dereference on shared blocks\n\nThe old-method path in fw_classify() calls tcf_block_q() and\ndereferences q->handle.  Shared blocks leave block->q NULL, causing a\nNULL deref when an empty cls_fw filter is attached to a shared block\nand a packet with a nonzero major skb mark is classified.\n\nReject the configuration in fw_change() when the old method (no\nTCA_OPTIONS) is used on a shared block, since fw_classify()'s\nold-method path needs block->q which is NULL for shared blocks.\n\nThe fixed null-ptr-deref calling stack:\n KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]\n RIP: 0010:fw_classify (net/sched/cls_fw.c:81)\n Call Trace:\n  tcf_classify (./include/net/tc_wrapper.h:197 net/sched/cls_api.c:1764 net/sched/cls_api.c:1860)\n  tc_run (net/core/dev.c:4401)\n  __dev_queue_xmit (net/core/dev.c:4535 net/core/dev.c:4790)",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "d6d5bd62a09650856e1e2010eb09853eba0d64e1"
            },
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "febf64ca79a2d6540ab6e5e197fa0f4f7e84473e"
            },
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "3d41f9a314afa94b1c7c7c75405920123220e8cd"
            },
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "18328eff2f97d1a6adcdb6d4a0f42f2f83a31e28"
            },
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "5cf41031922c154aa5ccda8bcdb0f5e6226582ec"
            },
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "3cb055df9e8625ce699a259d8178d67b37f2b160"
            },
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "96426c348def662b06bfdc65be3002905604927a"
            },
            {
              "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
              "status": "affected",
              "versionType": "git",
              "lessThan": "faeea8bbf6e958bf3c00cb08263109661975987c"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "4.15",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "4.15"
            },
            {
              "version": "5.10.253",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.15.203",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "6.1.168",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "version": "6.6.134",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "version": "6.12.81",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.18.22",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "version": "6.19.12",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.19.*"
            },
            {
              "version": "7.0",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}