CVE-2026-63956 USB: serial: cypress_m8: fix memory corruption with small endpoint
A malicious USB device can trigger memory corruption in the Linux kernel cypress_m8 driver, potentially leading to code execution or system crash.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-63956?
CVE-2026-63956 is a memory corruption vulnerability in Linux, published on 19 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
USB: serial: cypress_m8: fix memory corruption with small endpoint
Make sure that the interrupt-out endpoint max packet size is at least eight bytes to avoid user-controlled slab corruption or NULL-pointer dereference should a malicious device report a smaller size.
Which versions are affected by CVE-2026-63956?
How do I fix CVE-2026-63956?
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-2026-63956 being exploited?
There is no known exploitation of CVE-2026-63956 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-63956, DEBIAN-CVE-2026-63956, GHSA-4m78-mjgq-hq8g, ROOT-OS-UBUNTU-2204-CVE-2026-63956, UBUNTU-CVE-2026-63956.