{
  "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-2026-98299",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-98299",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-10-06T08:45:57.226Z",
    "updatedAt": "2026-10-19T09:17:10.154Z",
    "importedAt": "2026-10-24T01:58:41.756Z",
    "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": "tcp: do not let tcp_rmem be set below 4096",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: do not let tcp_rmem be set below 4096\n\nWe can hit a division by zero crash in tcp_rcvbuf_grow()\nand tcp_rcv_space_adjust():\n\ndivide error: 0000 [#1] PREEMPT SMP\nRIP: 0010:tcp_rcvbuf_grow+0x187/0x450 net/ipv4/tcp_input.c:939\n...\ngrow = div_u64(((u64)rcvwin << 1) * (newval - oldval), oldval);\n\nThe division uses oldval = tp->rcvq_space.space as divisor.\nWhen tp->rcvq_space.space is zero, this leads to a divide-by-zero\nexception.\n\ntp->rcvq_space.space is initialized in tcp_init_buffer_space():\n    tp->rcvq_space.space = min3(tp->rcv_ssthresh, tp->rcv_wnd,\n                                (u32)TCP_INIT_CWND * tp->advmss);\n\nIf tcp_rmem[1] is configured to very small values (such as 1),\nsk->sk_rcvbuf is initialized to 1. Then tcp_full_space(sk), which\ncomputes (sk->sk_rcvbuf * scaling_ratio) >> 8, truncates to 0.\nThis sets tp->window_clamp = 0, tp->rcv_ssthresh = 0, and\ntp->rcvq_space.space = 0. Later, when data arrives and DRS is invoked,\ntcp_rcvbuf_grow() divides by oldval == 0.\n\nBack in 2015, commit b1cb59cf2efe (\"net: sysctl_net_core: check SNDBUF\nand RCVBUF for min length\") ensured that net.core.rmem_default and\nnet.core.rmem_max cannot be set below SOCK_MIN_RCVBUF. Similarly,\nSO_RCVBUF setsockopt enforces max_t(int, val * 2, SOCK_MIN_RCVBUF).\n\nHowever, net.ipv4.tcp_rmem still had .extra1 = SYSCTL_ONE, allowing\narbitrarily small values.\n\nBecause SOCK_MIN_RCVBUF depends on sizeof(struct sk_buff) and cacheline\nalignment, its value varies across architectures and configuration options.\nUsing a fixed constant of 4096 ensures a predictable, architecture-\nindependent lower bound that is safely above SOCK_MIN_RCVBUF everywhere\nand matches the documented 4K default.\n\nFix this by setting tcp_rmem.extra1 to 4096 and updating the documentation.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "879907631b9e70eedb62d76461b29afa106ebe7a"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "8e32532d0fa3191ecf9524b0e6bafa0832e712ba"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "67b83c15bed9eeeb8d1a6dbf88a5f79525970173"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "9a4f49bf8d2da4e52e904f60c29cca317bab9b3a"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "60df201dbb19a1bf6478b56d100f7ae1fe90e46a"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "7898bda1ebc198f5559b301a96dd5398edd4d4d3"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "1c4bb940c3bb4325bb88ac1b7eaf5faaa39e7d63"
            },
            {
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "status": "affected",
              "versionType": "git",
              "lessThan": "83a945a529d6e002dd7339c532288a931f463dba"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "2.6.12",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "2.6.12"
            },
            {
              "version": "5.10.271",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.15.222",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "6.1.189",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "version": "6.6.158",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "version": "6.12.112",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.18.54",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "version": "7.2.8",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "version": "7.3",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}