{"id":"CVE-2026-80946","title":"fuse: copy request headers via a stack buffer for io-uring","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nfuse: copy request headers via a stack buffer for io-uring\n\nThe fuse-io-uring transport copies req->in.h out to the ring in\nfuse_uring_copy_to_ring() and req->out.h bac…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-501"],"vendor":"Linux","product":"Linux","affected":["Linux >= c090c8abae4b6b77a1bee116aa6c385456ebef96 < 194d0fb0ea4720535ff3168c9d04c7632cec7071","Linux >= c090c8abae4b6b77a1bee116aa6c385456ebef96 < a47a416ff68d706dc3327ab583f86b9ee757358b","Linux >= c090c8abae4b6b77a1bee116aa6c385456ebef96 < fd10f40af314f07b6d6e028b1ca25c8b49903aab","Linux 6.14"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:45:30.291Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80946","references":[{"url":"https://git.kernel.org/stable/c/194d0fb0ea4720535ff3168c9d04c7632cec7071"},{"url":"https://git.kernel.org/stable/c/a47a416ff68d706dc3327ab583f86b9ee757358b"},{"url":"https://git.kernel.org/stable/c/fd10f40af314f07b6d6e028b1ca25c8b49903aab"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80946.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-80946"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532123"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-80946"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80946"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80946.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00166,"epssPercentile":0.05797,"ingestedAt":"2026-09-14T00:35:28.532Z","slug":"CVE-2026-80946","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nfuse: copy request headers via a stack buffer for io-uring\n\nThe fuse-io-uring transport copies req->in.h out to the ring in\nfuse_uring_copy_to_ring() and req->out.h back in fuse_uring_commit().\nBoth headers live inside the fuse_request slab object, whose cache\n(fuse_req_cachep) is created without a usercopy whitelist, so copying\nthem directly to/from userspace trips CONFIG_HARDENED_USERCOPY and\npanics:\n\n  usercopy: Kernel memory exposure attempt detected from SLUB object\n  'fuse_request' (offset 56, size 40)!\n  kernel BUG at mm/usercopy.c:102!\n  Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI\n  RIP: 0010:usercopy_abort (mm/usercopy.c:90)\n  Call Trace:\n   __check_heap_object (mm/slub.c:8268)\n   __check_object_size (mm/usercopy.c:197 mm/usercopy.c:258 mm/usercopy.c:223)\n   copy_header_to_ring (fs/fuse/dev_uring.c:618)\n   fuse_uring_prepare_send (fs/fuse/dev_uring.c:776 fs/fuse/dev_uring.c:785)\n   fuse_uring_send_in_task (fs/fuse/dev_uring.c:1306)\n   tctx_task_work_run (io_uring/tw.c:96)\n   task_work_run (kernel/task_work.c:233)\n   io_run_task_work (io_uring/tw.h:84)\n   io_cqring_wait (io_uring/wait.c:278)\n   __do_sys_io_uring_enter (io_uring/io_uring.c:2685)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n\nBounce both headers through an on-stack copy so the usercopy touches\nstack memory, not the slab object.\n\n## Affected\n\n- `Linux >= c090c8abae4b6b77a1bee116aa6c385456ebef96 < 194d0fb0ea4720535ff3168c9d04c7632cec7071`\n- `Linux >= c090c8abae4b6b77a1bee116aa6c385456ebef96 < a47a416ff68d706dc3327ab583f86b9ee757358b`\n- `Linux >= c090c8abae4b6b77a1bee116aa6c385456ebef96 < fd10f40af314f07b6d6e028b1ca25c8b49903aab`\n- `Linux 6.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80946.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":202732,"id":"CVE-2026-80946","ts":1789403715345,"field":"cvss","old":null,"new":"5.5"},{"seq":202731,"id":"CVE-2026-80946","ts":1789403715345,"field":"severity","old":"none","new":"medium"},{"seq":147742,"id":"CVE-2026-80946","ts":1789270212115,"field":"cvss","old":null,"new":"5.3"},{"seq":147741,"id":"CVE-2026-80946","ts":1789270212115,"field":"severity","old":"none","new":"medium"},{"seq":109500,"id":"CVE-2026-80946","ts":1789183732154,"field":"cvss","old":null,"new":"5.3"},{"seq":109499,"id":"CVE-2026-80946","ts":1789183732154,"field":"severity","old":"none","new":"medium"}]}