CVE-2026-63898 USB: serial: mct_u232: fix memory corruption with small endpoint
A malicious USB device can trigger memory corruption in the mct_u232 driver, potentially allowing local attackers to execute code or escalate privileges.
- 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-2026-63898?
CVE-2026-63898 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: mct_u232: fix memory corruption with small endpoint
The driver overrides the maximum transfer size for a specific device which only accepts 16 byte packets for its 32 byte bulk-out endpoint.
Make sure to never increase the maximum transfer size to prevent slab corruption should a malicious device report a smaller endpoint max packet size than expected.
Which versions are affected by CVE-2026-63898?
How do I fix CVE-2026-63898?
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-2026-63898 being exploited?
There is no known exploitation of CVE-2026-63898 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-63898, DEBIAN-CVE-2026-63898, GHSA-6rff-3vpp-qcmx, ROOT-OS-UBUNTU-2204-CVE-2026-63898, UBUNTU-CVE-2026-63898.