CVE-2026-63903 USB: serial: belkin_sa: validate interrupt status length
A missing length check in the Belkin USB serial driver allows out-of-bounds reads, potentially causing kernel crashes or information disclosure via local physical access.
- 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-2026-63903?
CVE-2026-63903 is a memory corruption vulnerability in Linux, published on 19 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: serial: belkin_sa: validate interrupt status length
The Belkin interrupt callback treats interrupt data as a four-byte status report and reads LSR/MSR fields at offsets 2 and 3. The interrupt-in buffer length is derived from endpoint wMaxPacketSize, and short interrupt transfers may complete successfully with a smaller actual_length.
Check the completed interrupt packet length before parsing status fields so short interrupt endpoints and short successful packets are ignored instead of causing out-of-bounds or stale status-byte reads.
KASAN report as below:
BUG: KASAN: slab-out-of-bounds in belkin_sa_read_int_callback() Read of size 1 Call trace: belkin_sa_read_int_callback() (drivers/usb/serial/belkin_sa.c:202) __usb_hcd_giveback_urb() (drivers/usb/core/hcd.c:1630) dummy_timer() (?:?)
Which versions are affected by CVE-2026-63903?
How do I fix CVE-2026-63903?
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-2026-63903 being exploited?
There is no known exploitation of CVE-2026-63903 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-63903, DEBIAN-CVE-2026-63903, GHSA-5c4f-qfw8-c34w, ROOT-OS-UBUNTU-2204-CVE-2026-63903, UBUNTU-CVE-2026-63903.