Out-of-bounds write in Linux kernel - CVE-2026-98447

Vulnerability identifier: #VU156745

CSH Severity: Low

CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98447

CWE-ID: CWE-787

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to corrupt kernel memory, potentially causing a denial of service.

The vulnerability exists due to an out-of-bounds write in the XFS xfs_rtrefcountbt_from_disk() and xfs_rtrefcountbt_to_disk() functions when converting realtime refcount btree roots between on-disk and in-memory formats. A local user can trigger root formatting operations that copy twice the required key data to corrupt memory beyond the destination buffer, potentially causing a denial of service.

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/2703b954d306ebfe3b11e33e259759329c11b690
• https://git.kernel.org/stable/c/d46492fb8018d12d00651b06b9d240e747110b38
• https://git.kernel.org/stable/c/fe2f9135df43db849e74f03956d322ac20b59af7

• Out-of-bounds write in Linux kernel xfs libxfs
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more