Out-of-bounds read in Linux kernel - CVE-2026-98631

Vulnerability identifier: #VU156942

CSH Severity: Low

CVSS v4: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98631

CWE-ID: CWE-125

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to read out-of-bounds kernel memory, potentially disclosing sensitive information.

The vulnerability exists due to an out-of-bounds read in the Linux kernel's xsk_map_gen_lookup() function when generated lookup code compares a zero-extended 32-bit key against a sign-extended 64-bit bound. A local user can supply an out-of-range lookup key that bypasses the bounds check to read beyond the xsk_map[] array.

Exploitation requires a map with max_entries set to 0x80000000 or higher.

Linux kernel
Ubuntu
linux-nvidia-tegra (Ubuntu package)
linux-nvidia-tegra-igx (Ubuntu package)
linux-nvidia-tegra-5.15 (Ubuntu package)
linux (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-nvidia-tegra (Ubuntu package) - update to 5.15.0-1070.72
linux-nvidia-tegra-igx (Ubuntu package) - update to 5.15.0-1059.59
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1070.72~20.04.1
linux (Ubuntu package) - update to 7.0.0-42.42
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17

• https://git.kernel.org/stable/c/11d9be35c1f4233798e99be98bc474f83a254c6c
• https://git.kernel.org/stable/c/123f90f394ca404ab8796a7c8072ff7fa5b65a9c
• https://git.kernel.org/stable/c/227ec890559e922e235eb543646e3bf0bd8269b0
• https://git.kernel.org/stable/c/36461e58f88a1b723f86693f437ac12e60ff4363
• https://git.kernel.org/stable/c/3c1e0a4bc156b8d5c5772dbc76b9ea74dce5ca24
• https://git.kernel.org/stable/c/70504de0bb627848667207bec7ccfd647deb8814
• https://git.kernel.org/stable/c/b5c0cff0c5331582ab01c4c423731453a8381acc
• https://git.kernel.org/stable/c/c6d5c582d55a8f229d75e98d62eaa065b0deb18d

• Out-of-bounds read in Linux kernel xdp
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more
• Ubuntu update for linux-nvidia-tegra, linux-nvidia-tegra-5.15, linux-nvidia-tegra-igx
• Ubuntu update for linux, linux-aws, linux-aws-5.15 and more