CVE-2026-64259

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

Published Jul 25, 2026 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
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

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8726-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8727-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8728-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8760-1 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8726-2 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-8726-3 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8800-1 Linux kernel (NVIDIA BaseOS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8760-2 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8726-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8728-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8728-3 Linux kernel (Oracle) vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-416
Type Values Removed Values Added
Weaknesses CWE-416
Type Values Removed Values Added
Weaknesses CWE-416
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
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.
Title fuse-uring: make a fuse_req on SQE commit only findable after memcpy
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Aug 17, 2026, 4:52 AM
Reserved
Jul 19, 2026, 3:36 PM
Status
Analyzed
Published
Jul 25, 2026, 10:17 AM
Modified
Aug 17, 2026, 5:17 AM
Severity
Public date
Jul 25, 2026, 12:00 AM