Improper input validation in Linux kernel - CVE-2026-63956
Published: July 20, 2026
Vulnerability identifier: #VU138693
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-63956
CWE-ID: CWE-20
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows an attacker with physical access to cause a denial of service or corrupt memory.
The vulnerability exists due to improper input validation in the cypress_m8 USB serial driver when processing a malicious USB device with a too-small interrupt-out endpoint max packet size. An attacker with physical access can connect a specially crafted USB device to cause a denial of service or corrupt memory.
The issue can be triggered if a device reports an interrupt-out endpoint max packet size smaller than eight bytes.
How to mitigate CVE-2026-63956
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/1ef25704bd3b625fd151c09feee459479f71ee64
- https://git.kernel.org/stable/c/284105c40fc31fff90cdab8a0377aaeb92f87f0e
- https://git.kernel.org/stable/c/4bcaa59f403dbde6328604a500d65ee8d40975d9
- https://git.kernel.org/stable/c/4fcb22218f0a7229b7ce3b3952fb644def293fa5
- https://git.kernel.org/stable/c/52e18ae0c47c5c89e18fcd8022f287f7cc8802ec
- https://git.kernel.org/stable/c/6c13f3bb652bc8665e709ba07122612586aea648
- https://git.kernel.org/stable/c/ad3d1628a46134276546d7a12fedf04be9979158
- https://git.kernel.org/stable/c/e1a9d791fd66ab2431b9e6f6f835823809869047