CVE-2026-64259 fuse-uring: make a fuse_req on SQE commit only findable after memcpy
A use-after-free vulnerability in the Linux kernel's fuse-uring module allows malicious userspace to trigger memory corruption, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64259?
CVE-2026-64259 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-416
Which versions are affected by CVE-2026-64259?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64259?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-64259 being exploited?
There is no known exploitation of CVE-2026-64259 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64259, DEBIAN-CVE-2026-64259, GHSA-6vp8-rvj5-gc8c, ROOT-OS-UBUNTU-2204-CVE-2026-64259, UBUNTU-CVE-2026-64259.