Use-after-free in Linux kernel - CVE-2026-98563

Vulnerability identifier: #VU156867

CSH Severity: Low

CVSS v4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98563

CWE-ID: CWE-416

Exploitation vector: Local access

Exploit availability: No public exploit available

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

The vulnerability exists due to use-after-free in the Linux kernel phylink subsystem when a failed PHY connection leaves a stale pl->phydev pointer after the PHY is detached and freed. A local user can trigger this failure condition and subsequent access to the stale pointer to potentially crash the kernel or disrupt network connectivity.

The affected failure path involves a MAC whose phylink operations implement LPI.

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/4e7a4af364c2048bafb213bf0ef4a89dcbe1bfd4
• https://git.kernel.org/stable/c/671a68654a9d319d7f0d53a6321db3d9b391bdef
• https://git.kernel.org/stable/c/a940003f44e7e441c228151dd212642152700ec8

• Use-after-free in Linux kernel net phy driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more