CVE-2026-64259

/// Technical description

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

fuse-uring: make a fuse_req on SQE commit only findable after memcpy

Bad userspace might try to trick us and send commit SQEs request

unique / commit-id of requests that are not even send to

fuse-server (io_uring_cmd_done() not called) yet.

fuse_uring_commit_fetch() ends the fuse request when the ring entry

has a wrong state, but that could have caused a use-after-free

with the memcpy operations in fuse_uring_send_in_task().

In order to avoid such races the call of fuse_uring_add_to_pq()

is moved after the copy operations and just before completing

the io-uring request - malicious userspace cannot find the request

anymore until all prepration work in fuse-client/kernel is completed.

This also moves fuse_uring_add_to_pq() a bit up in the code to

avoid a forward declaration. Also not with a preparation commit,

to make it easier to back port to older kernels.

/// 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