Out-of-bounds write in Linux kernel - CVE-2026-63962

Vulnerability identifier: #VU138682

CSH Severity: High

CVSS v4: 7.2 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-63962

CWE-ID: CWE-787

Exploitation vector: Adjecent network

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to overwrite adjacent memory.

The vulnerability exists due to an out-of-bounds write in svdm_consume_modes() when processing an unsolicited Discover Modes ACK containing crafted VDOs from a connected port partner. A remote attacker can send a crafted Discover Modes ACK to overwrite adjacent memory.

Exploitation is possible after the port partner is set because incoming Discover Modes ACK messages are consumed without being correlated to a request sent by the port.

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/3389c149c68c3fea61910ad5d34f7bf3bff44e32
• https://git.kernel.org/stable/c/4505f33dab56c274e82f47f94bf60a8cbf8f4b42
• https://git.kernel.org/stable/c/845598b154b9a92e9d279fafafa9405c121ae805
• https://git.kernel.org/stable/c/cbad85b446c06adbc5e5bed565871bb918ce9d32

• Out-of-bounds write in Linux kernel typec tcpm 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