Out-of-bounds write in Linux kernel - CVE-2026-98867

Vulnerability identifier: #VU157236

CSH Severity: Low

CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98867

CWE-ID: CWE-787

Exploitation vector: Local access

Exploit availability: No public exploit available

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

The vulnerability exists due to an out-of-bounds write in the Linux kernel dm-pcache component when replaying persistent cache keys with unchecked logical offsets. A local privileged user can supply a malformed key through controlled cache-device metadata to cause get_subtree() to form a pointer outside req_key_tree->subtrees[], which rb_insert() subsequently writes through.

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/10449703200076980704894c3d68d6796182371b
• https://git.kernel.org/stable/c/3d5a87cb909c1f375f08065b20123fa5db5958d8
• https://git.kernel.org/stable/c/97fc4b53dbe4a983fdf093243067fa6a64562307

• Out-of-bounds write in Linux kernel md dm-pcache driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more