SB2026091729 - Use-after-free in Linux kernel kvm mmu

Description

This security bulletin contains information about 1 vulnerability.

1) Use-after-free (CVE-ID: CVE-2026-89928)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to compromise confidentiality, integrity, and availability.

The vulnerability exists due to a use-after-free in the KVM x86 MMU lockless rmap walk when performing lockless rmap aging while a writer populates or frees an rmap. A local user can trigger lockless rmap aging concurrently with rmap modification to compromise confidentiality, integrity, and availability.

The issue requires CONFIG_KVM_MMU_LOCKLESS_AGING to be enabled.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/41debfc98526c0a95c41a62435aca0a70340a26d
• https://git.kernel.org/stable/c/8edb3c09e43f7cd8a5dfd291c6e0fc9c74d4621d
• https://git.kernel.org/stable/c/e428f9779a43737d830111238816f1928b07aefb