Out-of-bounds read in Linux kernel - CVE-2026-98401

Vulnerability identifier: #VU155917

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-2026-98401

CWE-ID: CWE-125

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to an out-of-bounds read caused by a stale transport-header offset in qdisc_pkt_len_segs_init() when processing decapsulated packets carrying GSO metadata. A local user can supply a specially crafted encapsulated packet to cause a denial of service.

Exploitation requires the inner frame to be forwarded at layer 2 through a bridge or HSR rather than delivered to the local IP stack. The affected packet-processing path uses gro_cells and reaches __dev_queue_xmit().

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/28a57fb2c5df4deb42a06e52fd36c14b37aa0034
• https://git.kernel.org/stable/c/3340b8565b85631cfeb0df049e8b46e3ef8bd7bd
• https://git.kernel.org/stable/c/8c3d4dfcecf7670c1d752f1ae74b21b2af5feac1
• https://git.kernel.org/stable/c/e4a5b01e59f7102169762b8f566c8e052d05c0ff

• Out-of-bounds read in Linux kernel core
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more