CVE-2026-64328 usb: gadget: f_fs: Fix DMA fence leak
A memory leak in the Linux kernel USB gadget functionfs driver allows attackers to exhaust system memory, causing denial of service.
- 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-2026-64328?
CVE-2026-64328 is a medium-severity memory corruption 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:
usb: gadget: f_fs: Fix DMA fence leak
In ffs_dmabuf_transfer(), a ffs_dma_fence object is kmalloc'd, with the underlying dma_fence later initialized by dma_fence_init(), which sets its kref counter to 1. Then, dma_resv_add_fence() gets a second reference, and a pointer to the ffs_dma_fence is passed as the usb_request's "context" field.
The dma-resv mechanism will manage the second reference, but the first reference is never properly released; the ffs_dmabuf_cleanup() function decreases the reference count, but only to balance with the reference grab in ffs_dmabuf_signal_done().
The code will then slowly leak memory as more ffs_dma_fence objects are created without being ever freed.
Address this issue by transferring ownership of the fence to the DMA reservation object, by calling dma_fence_put() right after dma_resv_add_fence(). The ffs_dma_fence then gets properly discarded after being signalled.
Weakness: CWE-401
Which versions are affected by CVE-2026-64328?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64328?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-64328 being exploited?
There is no known exploitation of CVE-2026-64328 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64328, DEBIAN-CVE-2026-64328, GHSA-rwqh-f7g9-w86h, ROOT-OS-UBUNTU-2204-CVE-2026-64328, UBUNTU-CVE-2026-64328.