SB20260720287 - Improper Initialization in Linux kernel mm

Description

This security bulletin contains information about 1 vulnerability.

1) Improper Initialization (CVE-ID: CVE-2026-63950)

CWE-ID: CWE-665 - Improper Initialization

CVSSv4: 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]

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

The vulnerability exists due to improper initialization in try_to_unmap_one() in mm/rmap.c when reclaiming a lazyfree anonymous folio with device-exclusive page table entries. A local user can trigger reclaim after arranging the affected memory state to cause a denial of service.

Exploitation requires a sequence involving a MAP_ANONYMOUS | MAP_DROPPABLE mapping, MADV_FREE, and making the last page device-exclusive via HMM_DMIRROR_EXCLUSIVE.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/0fcc34d0d8fefca4fea349e45c10e3a3d90350eb
• https://git.kernel.org/stable/c/3f8968e9cbf95d5d87d32218906cab0b9b9eddbe
• https://git.kernel.org/stable/c/f611db9b771b2b6775357555d2517af044fca4f0