CVE-2026-64263

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

fuse-uring: fix moving cancelled entry to ent_in_userspace list

fuse_uring_cancel() moves entries that are available (these have no reqs

attached) to the ent_in_userspace list. ent_list_request_expired()

checks the first entry on ent_in_userspace and dereferences

ent->fuse_req unconditionally, which will crash on a cancelled entry

that was moved to this list.

Fix this by freeing the entry and dropping queue_refs directly in

fuse_uring_cancel(). This is safe because cancel is the cancel handler

itself - after io_uring_cmd_done(), no more cancels will be dispatched

for this command, and teardown serializes with cancel via queue->lock.

Since cancel now decrements queue_refs, fuse_uring_abort() must no

longer gate fuse_uring_abort_end_requests() on queue_refs > 0, as

cancelled entries may have already dropped queue_refs while requests are

still queued. Remove the gate so abort always flushes requests and stops

queues.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References