{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "427faee167bce4ccb0b22f6815a9ac509e31d4c3"
            },
            {
              "fixed": "1d56a00ec91f2885c64ea5b8cea18cb746b91bbb"
            },
            {
              "fixed": "ce66352d3eb21825410af8b91db7cc4bb8e22c98"
            },
            {
              "fixed": "e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc"
            },
            {
              "fixed": "0ae10b6be49b425827659b23bcce498f80eb7182"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.15.0"
            },
            {
              "fixed": "6.12.111"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.53"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97984.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: Fix UDP length overflow with PMTU discover and big MTU\n\nThis commit bounds cork-\u003ebase.fragsize to IP6_MAX_MTU for UDP sockets to\navoid a possible overflow of UDP length that triggers a WARN in\nudp_set_len_short when setsockopt IPV6_MTU_DISCOVER is set to\nIPV6_PMTUDISC_DO or IPV6_PMTUDISC_PROBE, and a large packet is sent over\na netdev with an unusually large MTU.\n\nSteps to reproduce (included in the new selftest):\n\n1. Set device MTU bigger than IP6_MAX_MTU. cork-\u003ebase.fragsize will be\n   set to that MTU in ip6_setup_cork.\n2. Set IPV6_MTU_DISCOVER to IPV6_PMTUDISC_PROBE or IPV6_PMTUDISC_DO. It\n   lets maxnonfragsize be set to device MTU (cork-\u003efragsize) in\n   __ip6_append_data, rather than to IP6_MAX_MTU.\n3. Send 65528 bytes of payload (+8 bytes of UDP header, +40 bytes of\n   IPv6 header). Device MTU allows it (it's only one byte bigger than\n   IP6_MAX_MTU, and the device MTU is bigger than that).\n4. The UDP length in the built packet is 65536, which overflows the\n   16-bit length field and triggers the WARN in udp_set_len_short.\n\nTo avoid breaking sending UDP jumbograms over raw IPv6 sockets, limit\nthe change to UDP sockets only.\n\nThe original overflow bug with IPv6 and IPV6_PMTUDISC_DO seems to\npredate git history (verified reproduction on 2.6.21), was fixed later,\nand then reappeared in commit 427faee167bc (\"net: ipv6: introduce\nip6_dst_mtu_maybe_forward\"), which is chosen as the Fixes tag here. The\noverflow with IPV6_PMTUDISC_PROBE reproduces since its introduction in\ncommit 628a5c561890 (\"[INET]: Add IP(V6)_PMTUDISC_RPOBE\").",
  "id": "CVE-2026-97984",
  "modified": "2026-09-27T03:30:39.713746656Z",
  "published": "2026-09-25T10:23:19.568Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0ae10b6be49b425827659b23bcce498f80eb7182"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1d56a00ec91f2885c64ea5b8cea18cb746b91bbb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ce66352d3eb21825410af8b91db7cc4bb8e22c98"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e01b7c176d9af2b7c22bb3fe12cf9a7904f99fdc"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97984.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97984"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "net: ipv6: Fix UDP length overflow with PMTU discover and big MTU"
}