{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2"
            },
            {
              "fixed": "879907631b9e70eedb62d76461b29afa106ebe7a"
            },
            {
              "fixed": "8e32532d0fa3191ecf9524b0e6bafa0832e712ba"
            },
            {
              "fixed": "67b83c15bed9eeeb8d1a6dbf88a5f79525970173"
            },
            {
              "fixed": "9a4f49bf8d2da4e52e904f60c29cca317bab9b3a"
            },
            {
              "fixed": "60df201dbb19a1bf6478b56d100f7ae1fe90e46a"
            },
            {
              "fixed": "7898bda1ebc198f5559b301a96dd5398edd4d4d3"
            },
            {
              "fixed": "1c4bb940c3bb4325bb88ac1b7eaf5faaa39e7d63"
            },
            {
              "fixed": "83a945a529d6e002dd7339c532288a931f463dba"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.12"
            },
            {
              "fixed": "5.10.271"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.222"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.189"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.158"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.112"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.54"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98299.json"
  },
  "details": "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 \u003c\u003c 1) * (newval - oldval), oldval);\n\nThe division uses oldval = tp-\u003ercvq_space.space as divisor.\nWhen tp-\u003ercvq_space.space is zero, this leads to a divide-by-zero\nexception.\n\ntp-\u003ercvq_space.space is initialized in tcp_init_buffer_space():\n    tp-\u003ercvq_space.space = min3(tp-\u003ercv_ssthresh, tp-\u003ercv_wnd,\n                                (u32)TCP_INIT_CWND * tp-\u003eadvmss);\n\nIf tcp_rmem[1] is configured to very small values (such as 1),\nsk-\u003esk_rcvbuf is initialized to 1. Then tcp_full_space(sk), which\ncomputes (sk-\u003esk_rcvbuf * scaling_ratio) \u003e\u003e 8, truncates to 0.\nThis sets tp-\u003ewindow_clamp = 0, tp-\u003ercv_ssthresh = 0, and\ntp-\u003ercvq_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.",
  "id": "CVE-2026-98299",
  "modified": "2026-10-07T02:30:36.382574525Z",
  "published": "2026-10-06T08:45:57.226Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1c4bb940c3bb4325bb88ac1b7eaf5faaa39e7d63"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/60df201dbb19a1bf6478b56d100f7ae1fe90e46a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/67b83c15bed9eeeb8d1a6dbf88a5f79525970173"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7898bda1ebc198f5559b301a96dd5398edd4d4d3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/83a945a529d6e002dd7339c532288a931f463dba"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/879907631b9e70eedb62d76461b29afa106ebe7a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8e32532d0fa3191ecf9524b0e6bafa0832e712ba"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9a4f49bf8d2da4e52e904f60c29cca317bab9b3a"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98299.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98299"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "tcp: do not let tcp_rmem be set below 4096"
}