netfilter: flowtable: support IPIP tunnel with direct xmit

{
  "id": "1a307b0c714cb47fce454e05a3fa2f1d960ae444b6de896cd0a1d315e8df7a3b",
  "url": "https://osv.dev/vulnerability/CVE-2026-72248",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "netfilter: flowtable: support IPIP tunnel with direct xmit",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: support IPIP tunnel with direct xmit The combination of IPIP tunnel with direct xmit, eg. bridge device, breaks because no dst_entry is provided to check the skb headroom and to set the iph->frag_off field. This leads to invalid dst usage and can trigger a crash in the tunnel transmit path. Fix this by moving dst_cache and dst_cookie out of the runtime union so that they can be shared by neighbour, xfrm, and direct tunnel flows. For FLOW_OFFLOAD_XMIT_DIRECT tuples carrying tunnel metadata, preserve route state in these shared fields and release it through the common dst release path. Since dst_entry is now available to the three supported xmit modes and dst_release() already deals with NULL dst, remove the xmit type check in nft_flow_dst_release(). Moreover, skip the check if the dst entry is NULL in nf_flow_dst_check() which is now the case for the direct xmit case. Based on patch from Rein Wei .",
    "evidence": "osv:CVE-2026-72248",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.1.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-72248",
      "aliases": [
        "CVE-2026-72248"
      ],
      "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": [
                {
                  "introduced": "d30301ba4b07ac92eb38353a111833b009003170"
                },
                {
                  "fixed": "0880c4ed122d0cddc9f29a2b28f055d1f24f0fca"
                },
                {
                  "fixed": "fa7395c02d95e51bad2952325d2d6503bfbad437"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72248.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72248.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.692830596Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0880c4ed122d0cddc9f29a2b28f055d1f24f0fca",
        "https://git.kernel.org/stable/c/fa7395c02d95e51bad2952325d2d6503bfbad437",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72248.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-72248",
        "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/2026/72xxx/CVE-2026-72248.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-72248",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 502085,
  "published_at": "2026-08-15T05:54:36.535+00:00"
}