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.
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.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Sat, 12 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-501 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 11 Sep 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | fuse: copy request headers via a stack buffer for io-uring | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
Sign in to view the affected projects.
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-11T19:42:17.576Z
Reserved: 2026-08-26T14:34:25.803Z
Link: CVE-2026-80946
No data.
Status : Received
Published: 2026-09-11T20:19:00.180
Modified: 2026-09-11T20:19:00.180
Link: CVE-2026-80946
OpenCVE Enrichment
Updated: 2026-09-12T02:15:06Z
Weaknesses