Out-of-bounds read in Linux kernel - CVE-2026-63963

Vulnerability identifier: #VU138683

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-63963

CWE-ID: CWE-125

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to disclose sensitive information.

The vulnerability exists due to an out-of-bounds read in Discover Identity ACK handlers in the tcpm subsystem when processing a device-supplied VDO count. A remote attacker can provide a crafted count value to disclose sensitive information.

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/569f7971542eb10025d8a0989b83f28a29d8ba20
• https://git.kernel.org/stable/c/8fbc349e8383125dd2d8de1c1e926279d398ab17
• https://git.kernel.org/stable/c/ed8649f3822e211d025bcab5158af6f8a38c8705
• https://git.kernel.org/stable/c/f9d787fbe83127105e42088cca40e5118db0d810

• Out-of-bounds read 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