CVE-2026-74681 usb: misc: usbio: check ibuf_len against rxbuf_len in bulk msg
A logic error in the Linux kernel USB IO driver compares buffer sizes incorrectly, potentially allowing buffer over-reads or denial of service via crafted USB messages.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74681?
CVE-2026-74681 is a vulnerability in Linux, published on 22 Aug 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: misc: usbio: check ibuf_len against rxbuf_len in bulk msg
ibuf_len is the bulk IN (receive) buffer size, but the EMSGSIZE check in usbio_bulk_msg() compares it against txbuf_len — the bulk OUT endpoint size. Both are taken independently from different endpoints in usbio_probe(), so the check is wrong when they differ.
Use rxbuf_len for the IN direction. This matches the buffer that actually holds the response data.
Which versions are affected by CVE-2026-74681?
How do I fix CVE-2026-74681?
Apply the vendor's patch.
Is CVE-2026-74681 being exploited?
There is no known exploitation of CVE-2026-74681 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74681, DEBIAN-CVE-2026-74681, GHSA-c35q-c6r4-9764, UBUNTU-CVE-2026-74681.