FKIE_CVE-2026-74684

Vulnerability from fkie_nvd - Published: 2026-08-22 16:16 - Updated: 2026-10-14 13:10
Severity
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp() The commit 4f61f133f354 ("net: tap: NULL pointer derefence in dev_parse_header_protocol when skb->dev is null") fixed a crash in tap_get_user() by assigning skb->dev before calling tun_vnet_hdr_to_skb(). This is required because virtio_net_hdr_to_skb() may invoke dev_parse_header_protocol(), which dereferences skb->dev. Without the assignment, a NULL pointer dereference can occur. However, tap_get_user_xdp() still parses the virtio-net header before assigning skb->dev. When the vhost TX path passes an XDP buffer containing a GSO virtio-net header but the protocol is set to zero on purpose, tun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb->dev is still NULL, resulting in a crash. Fix this by looking up the tap device and assigning skb->dev before calling tun_vnet_hdr_to_skb(), matching the ordering already used in tap_get_user(). Preserve the existing RCU read-side critical section across dev_queue_xmit().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/15583b07fd691a844fbf7b3ad612cdc9e9a657c0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3874892dd27d5387aa9a06f58d9060f18f351d24
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8b444b126cd8e4473e652f529753ed4dd1360a9c
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/tap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "15583b07fd691a844fbf7b3ad612cdc9e9a657c0",
              "status": "affected",
              "version": "924a9bc362a5223cd448ca08c3dde21235adc310",
              "versionType": "git"
            },
            {
              "lessThan": "8b444b126cd8e4473e652f529753ed4dd1360a9c",
              "status": "affected",
              "version": "924a9bc362a5223cd448ca08c3dde21235adc310",
              "versionType": "git"
            },
            {
              "lessThan": "164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b",
              "status": "affected",
              "version": "924a9bc362a5223cd448ca08c3dde21235adc310",
              "versionType": "git"
            },
            {
              "lessThan": "3874892dd27d5387aa9a06f58d9060f18f351d24",
              "status": "affected",
              "version": "924a9bc362a5223cd448ca08c3dde21235adc310",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ea3fb2ce5fa794d02135f5c079e05cd6fc3f545d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "54ef8243c3c8e90f1ea5792e6752e021a25c8eb3",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "ca278267d6cd9544645731732455b6b20cb0e895",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "faa3baa2828c5e1c4374f3e60041f75c64f5fcb6",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "99b1d3f74b9ef72c2f74c8e4c078e1bc0706e748",
              "versionType": "git"
            },
            {
              "lessThan": "4.15",
              "status": "affected",
              "version": "4.14.226",
              "versionType": "semver"
            },
            {
              "lessThan": "4.20",
              "status": "affected",
              "version": "4.19.181",
              "versionType": "semver"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.106",
              "versionType": "semver"
            },
            {
              "lessThan": "5.11",
              "status": "affected",
              "version": "5.10.24",
              "versionType": "semver"
            },
            {
              "lessThan": "5.12",
              "status": "affected",
              "version": "5.11.7",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/tap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.12"
            },
            {
              "lessThan": "5.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.105",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tap: set skb-\u003edev before parsing virtio net header in tap_get_user_xdp()\n\nThe commit 4f61f133f354 (\"net: tap: NULL pointer derefence in\ndev_parse_header_protocol when skb-\u003edev is null\") fixed a crash in\ntap_get_user() by assigning skb-\u003edev before calling tun_vnet_hdr_to_skb().\nThis is required because virtio_net_hdr_to_skb() may invoke\ndev_parse_header_protocol(), which dereferences skb-\u003edev. Without the\nassignment, a NULL pointer dereference can occur.\n\nHowever, tap_get_user_xdp() still parses the virtio-net header before\nassigning skb-\u003edev. When the vhost TX path passes an XDP buffer containing\na GSO virtio-net header but the protocol is set to zero on purpose,\ntun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb-\u003edev\nis still NULL, resulting in a crash.\n\nFix this by looking up the tap device and assigning skb-\u003edev before calling\ntun_vnet_hdr_to_skb(), matching the ordering already used in\ntap_get_user(). Preserve the existing RCU read-side critical section across\ndev_queue_xmit()."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet: tap: establecer skb -\u003e dev antes de analizar el encabezado virtio net en tap_get_user_xdp()\n\nEl commit 4f61f133f354 (\u0027net: tap: desreferencia de puntero NULL en dev_parse_header_protocol cuando skb -\u003e dev es nulo\u0027) corrigi\u00f3 un fallo en tap_get_user() asignando skb -\u003e dev antes de llamar a tun_vnet_hdr_to_skb(). Esto es necesario porque virtio_net_hdr_to_skb() puede invocar a dev_parse_header_protocol(), que desreferencia skb -\u003e dev. Sin la asignaci\u00f3n, puede ocurrir una desreferencia de puntero NULL.\n\nSin embargo, tap_get_user_xdp() todav\u00eda analiza el encabezado virtio-net antes de asignar skb -\u003e dev. Cuando la ruta TX de vhost pasa un b\u00fafer XDP que contiene un encabezado virtio-net GSO pero el protocolo se establece a cero a prop\u00f3sito, tun_vnet_hdr_to_skb() puede alcanzar dev_parse_header_protocol() mientras skb -\u003e dev todav\u00eda es NULL, lo que resulta en un fallo.\n\nSolucionar esto buscando el dispositivo tap y asignando skb -\u003e dev antes de llamar a tun_vnet_hdr_to_skb(), igualando el orden ya utilizado en tap_get_user(). Preservar la secci\u00f3n cr\u00edtica de lectura RCU existente a trav\u00e9s de dev_queue_xmit()."
    }
  ],
  "id": "CVE-2026-74684",
  "lastModified": "2026-10-14T13:10:00.187",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.5,
        "impactScore": 4.0,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-22T16:16:42.757",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/15583b07fd691a844fbf7b3ad612cdc9e9a657c0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3874892dd27d5387aa9a06f58d9060f18f351d24"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8b444b126cd8e4473e652f529753ed4dd1360a9c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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