Improper input validation in Linux kernel - CVE-2026-98868

Vulnerability identifier: #VU157237

CSH Severity: Low

CVSS v4: 6.7 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98868

CWE-ID: CWE-20

Exploitation vector: Local access

Exploit availability: No public exploit available

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

The vulnerability exists due to insufficient validation of kset sizes in the Linux kernel dm-pcache component when processing on-media cache metadata during cache replay, writeback, or garbage collection. A local privileged user can supply cache metadata with a forged key_num value, if able to modify that metadata, to make the calculated kset size exceed the remaining segment space and trigger the cache_pos_advance() BUG_ON, 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/01a700e9278da5706c865b9ca3ae70fdb7b4531d
• https://git.kernel.org/stable/c/7ac1f10f987a2ffae4aecf0e2ceca8f552b665cb
• https://git.kernel.org/stable/c/96e2863b1f81ea61b8d8d5d5a45d3b4c018f8e10

• Improper input validation in Linux kernel md dm-pcache driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more