CVE-2026-64259

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/e1711479e9068ea31b31353a702a51e639c3d059
• https://git.kernel.org/stable/c/a635f427d57e2012102ae4886b48d8955c59fb86
• https://git.kernel.org/stable/c/1efd3d474fc0ba74dfd984249bca78807d739812

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