Integer overflow in Linux kernel - CVE-2026-63896

Vulnerability identifier: #VU138749

CSH Severity: Medium

CVSS v4: 5.1 [CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-63896

CWE-ID: CWE-190

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to an integer underflow leading to an out-of-bounds write in the WebUSB GET_URL handler in composite_setup() when processing a crafted USB SETUP packet. A remote attacker can send a specially crafted USB request to cause a denial of service.

Exploitation is possible against gadgets with webusb/use=1 and a landing page configured.

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• https://git.kernel.org/stable/c/046870ff6b6f7b743c953c061043a9b30700d491
• https://git.kernel.org/stable/c/6c5dbc104dadd79fc2923497c20bae759a18758c
• https://git.kernel.org/stable/c/a20f0ccf45708af6e063c7234c215d364b00de25
• https://git.kernel.org/stable/c/f5869dfaa89854dcf34121036294d42d6c7acb8f
• https://git.kernel.org/stable/c/f8f5a8f48c7cae3fac85e04b593bd47939f9725f

• Integer overflow in Linux kernel usb gadget driver
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia