openvswitch: fix GSO userspace truncation underflow

{
  "id": "51a6861506af23ac7bbea132efea3012a45b158bf46c7832e65fb1171aa37c32",
  "url": "https://osv.dev/vulnerability/CVE-2026-68123",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "openvswitch: fix GSO userspace truncation underflow",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix GSO userspace truncation underflow OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb length in OVS_CB(skb)->cutlen. When a later userspace action segments a GSO skb, queue_gso_packets() reuses that delta for each smaller segment. A segment can then reach queue_userspace_packet() with cutlen greater than skb->len, underflowing the length passed to skb_zerocopy(). Store the maximum preserved length instead and bound each consumer against the current skb length. Use U32_MAX as the no-truncation sentinel so the value remains valid if skb geometry changes before a consumer handles it.",
    "evidence": "osv:CVE-2026-68123",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.265",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.216",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.183",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.148",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.101",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.42",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-68123",
      "aliases": [
        "CVE-2026-68123"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1"
                },
                {
                  "fixed": "50a6a85f3d6b1d22d8436848606cdef5d2c490b4"
                },
                {
                  "fixed": "2623c48cc3a8da9a1886fd8f65c0e348f4406fd6"
                },
                {
                  "fixed": "e211b081901ffca76674082c73eeaed53524c369"
                },
                {
                  "fixed": "a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855"
                },
                {
                  "fixed": "fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc"
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                {
                  "fixed": "100a23b1613e9218e0af654ef102352c713f0263"
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                {
                  "fixed": "ea85dbcbe8d4056ecb54352f97743d138ea4c407"
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                  "fixed": "4032f8ed10fcb84d41c508dfb04be96589f78dfe"
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            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68123.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.8.0"
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                {
                  "fixed": "5.10.265"
                }
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
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            {
              "type": "ECOSYSTEM",
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                {
                  "introduced": "5.16.0"
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                {
                  "fixed": "6.1.183"
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            {
              "type": "ECOSYSTEM",
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                  "introduced": "6.2.0"
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.13.0"
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                {
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            },
            {
              "type": "ECOSYSTEM",
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                  "introduced": "6.19.0"
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68123.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.515234089Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/100a23b1613e9218e0af654ef102352c713f0263",
        "https://git.kernel.org/stable/c/2623c48cc3a8da9a1886fd8f65c0e348f4406fd6",
        "https://git.kernel.org/stable/c/4032f8ed10fcb84d41c508dfb04be96589f78dfe",
        "https://git.kernel.org/stable/c/50a6a85f3d6b1d22d8436848606cdef5d2c490b4",
        "https://git.kernel.org/stable/c/a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855",
        "https://git.kernel.org/stable/c/e211b081901ffca76674082c73eeaed53524c369",
        "https://git.kernel.org/stable/c/ea85dbcbe8d4056ecb54352f97743d138ea4c407",
        "https://git.kernel.org/stable/c/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68123.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-68123",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68123.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-68123",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504931,
  "published_at": "2026-08-10T11:58:43.727+00:00"
}