CVE-2026-64327 usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks

What is CVE-2026-64327?

CVE-2026-64327 is a medium-severity 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: Initialize epfile->in early to fix endpoint direction checks

When parsing endpoint descriptors, ffs_data_got_descs() generates the eps_addrmap which contains the endpoint direction. However, epfile->in was previously only populated in ffs_func_eps_enable() which executes upon USB host connection. As a result, early userspace ioctls like FUNCTIONFS_DMABUF_ATTACH that run before the host connects would see epfile->in as 0, leading to incorrect DMA directions.

By moving the initialization to ffs_epfiles_create(), epfile->in is accurate before userspace opens the endpoint files.

Which versions are affected by CVE-2026-64327?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-64327?

Apply the vendor's patch.

Is CVE-2026-64327 being exploited?

There is no known exploitation of CVE-2026-64327 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-64327, DEBIAN-CVE-2026-64327, GHSA-gjhh-5f46-ffh6, ROOT-OS-UBUNTU-2204-CVE-2026-64327, UBUNTU-CVE-2026-64327.