Integer overflow in Linux kernel - CVE-2026-98393

Vulnerability identifier: #VU155925

CSH Severity: Low

CVSS v4: 0 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98393

CWE-ID: CWE-190

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a local user to trigger a kernel warning.

The vulnerability exists due to integer overflow of the 16-bit UDP length field in the Linux kernel IPv4 packet construction code when constructing oversized UDP packets with IP_MTU_DISCOVER set to IP_PMTUDISC_PROBE. A local user can send a 65,528-byte UDP payload to trigger a kernel warning.

Exploitation requires a network device with an MTU greater than IP_MAX_MTU + 20.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (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 (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
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/81f540827d243b8dad76c1f44e70ea31719f393c
• https://git.kernel.org/stable/c/83fedc4741210f75be8ca5b487985a242bf6f18d
• https://git.kernel.org/stable/c/b83641e0ab8b20eefcc4cdc5a059f897375291a2

• Integer overflow in Linux kernel ipv4
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more