fuse: copy request headers via a stack buffer for io-uring

{
  "id": "1278091c603174a837cfa3db5193a2aa28f612ae855bc6efaf87f3738d87a427",
  "url": "https://osv.dev/vulnerability/CVE-2026-80946",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fuse: copy request headers via a stack buffer for io-uring",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: fuse: copy request headers via a stack buffer for io-uring The fuse-io-uring transport copies req->in.h out to the ring in fuse_uring_copy_to_ring() and req->out.h back in fuse_uring_commit(). Both headers live inside the fuse_request slab object, whose cache (fuse_req_cachep) is created without a usercopy whitelist, so copying them directly to/from userspace trips CONFIG_HARDENED_USERCOPY and panics: usercopy: Kernel memory exposure attempt detected from SLUB object 'fuse_request' (offset 56, size 40)! kernel BUG at mm/usercopy.c:102! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:usercopy_abort (mm/usercopy.c:90) Call Trace: __check_heap_object (mm/slub.c:8268) __check_object_size (mm/usercopy.c:197 mm/usercopy.c:258 mm/usercopy.c:223) copy_header_to_ring (fs/fuse/dev_uring.c:618) fuse_uring_prepare_send (fs/fuse/dev_uring.c:776 fs/fuse/dev_uring.c:785) fuse_uring_send_in_task (fs/fuse/dev_uring.c:1306) tctx_task_work_run (io_uring/tw.c:96) task_work_run (kernel/task_work.c:233) io_run_task_work (io_uring/tw.h:84) io_cqring_wait (io_uring/wait.c:278) __do_sys_io_uring_enter (io_uring/io_uring.c:2685) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Bounce both headers through an on-stack copy so the usercopy touches stack memory, not the slab object.",
    "evidence": "osv:CVE-2026-80946",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.51",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-80946",
      "aliases": [
        "CVE-2026-80946"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "c090c8abae4b6b77a1bee116aa6c385456ebef96"
                },
                {
                  "fixed": "194d0fb0ea4720535ff3168c9d04c7632cec7071"
                },
                {
                  "fixed": "a47a416ff68d706dc3327ab583f86b9ee757358b"
                },
                {
                  "fixed": "fd10f40af314f07b6d6e028b1ca25c8b49903aab"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80946.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.14.0"
                },
                {
                  "fixed": "6.18.51"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80946.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.380429766Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/194d0fb0ea4720535ff3168c9d04c7632cec7071",
        "https://git.kernel.org/stable/c/a47a416ff68d706dc3327ab583f86b9ee757358b",
        "https://git.kernel.org/stable/c/fd10f40af314f07b6d6e028b1ca25c8b49903aab",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80946.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-80946",
        "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/2026/80xxx/CVE-2026-80946.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-80946",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 492116,
  "published_at": "2026-09-11T19:42:17.576+00:00"
}