{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "1d036d25e5609ba73fee6a88db01c306b140d512"
            },
            {
              "fixed": "0f4c9754956b86de158a4af5278c5cf5bda9439e"
            },
            {
              "fixed": "714aa973da8163925eda7efd49361ccbee21ee46"
            },
            {
              "fixed": "1490f82353bdabc09265a74e645b07f05cf4188e"
            },
            {
              "fixed": "74e2db36fe50e3ad9d5300d7fd0e6e2a15a6d121"
            },
            {
              "fixed": "3a1bf9116ea31470b89692585c3910dfe830dcdd"
            },
            {
              "fixed": "28324a3b62d9ce7f9bdd65a8ce63f382041d1b27"
            },
            {
              "fixed": "48a6ef291a17639e1b6ae0fbe9c8b2bb87d7804b"
            },
            {
              "fixed": "2c054e17d9d41f1020376806c7f750834ced4dc5"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.6.0"
            },
            {
              "fixed": "5.10.259"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.210"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.176"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.136"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.84"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.25"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31700.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd()\n\nIn tpacket_snd(), when PACKET_VNET_HDR is enabled, vnet_hdr points\ndirectly into the mmap'd TX ring buffer shared with userspace. The\nkernel validates the header via __packet_snd_vnet_parse() but then\nre-reads all fields later in virtio_net_hdr_to_skb(). A concurrent\nuserspace thread can modify the vnet_hdr fields between validation\nand use, bypassing all safety checks.\n\nThe non-TPACKET path (packet_snd()) already correctly copies vnet_hdr\nto a stack-local variable. All other vnet_hdr consumers in the kernel\n(tun.c, tap.c, virtio_net.c) also use stack copies. The TPACKET TX\npath is the only caller of virtio_net_hdr_to_skb() that reads directly\nfrom user-controlled shared memory.\n\nFix this by copying vnet_hdr from the mmap'd ring buffer to a\nstack-local variable before validation and use, consistent with the\napproach used in packet_snd() and all other callers.",
  "id": "CVE-2026-31700",
  "modified": "2026-07-08T05:37:05.045612696Z",
  "published": "2026-05-01T13:56:00.205Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0f4c9754956b86de158a4af5278c5cf5bda9439e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1490f82353bdabc09265a74e645b07f05cf4188e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/28324a3b62d9ce7f9bdd65a8ce63f382041d1b27"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2c054e17d9d41f1020376806c7f750834ced4dc5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3a1bf9116ea31470b89692585c3910dfe830dcdd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/48a6ef291a17639e1b6ae0fbe9c8b2bb87d7804b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/714aa973da8163925eda7efd49361ccbee21ee46"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/74e2db36fe50e3ad9d5300d7fd0e6e2a15a6d121"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31700.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31700"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd()"
}