CVE-2026-89568

Received Received - Intake

Integer Overflow in Linux Kernel Memory Reservation

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: kho: fix size calculation in kho_preserved_memory_reserve() kho_preserved_memory_reserve() calculates the size of a preservation by doing 1 << (order + PAGE_SHIFT). Since the '1' is a 32-bit integer, it can only be shifted by 31. That is, it will only work for preservations up to 2 GiB. Larger preservations will trigger undefined behaviour. While preservations larger than 2 GiB can't be obtained via folios currently, they can be obtained via kho_preserve_pages(). For example, memblock reserve_mem uses kho_preserve_pages(). Reservations larger than 2 GiB are valid and will trigger this bug if properly aligned. Fix it by using 1UL for shifting.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-11

Last Modified

2026-09-11

Generated

2026-10-02

AI Q&A

2026-09-12

EPSS Evaluated

2026-10-01

NVD

CVE-2026-89568

EUVD

EUVD-2026-76479

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability is in the Linux kernel's kho_preserved_memory_reserve() function. It incorrectly calculates memory reservation sizes using a 32-bit integer, limiting reservations to 2 GiB. Larger reservations trigger undefined behavior. The fix involves using a 64-bit integer (1UL) for shifting to handle larger memory sizes.

Detection Guidance

This vulnerability is specific to the Linux kernel's memory reservation logic and does not have direct network detection methods. To check for affected systems, verify if your kernel version includes the vulnerable kho_preserved_memory_reserve() function. Use uname -a to check the kernel version and compare it against patched versions.

Impact Analysis

If exploited, this bug could cause system instability or crashes when memory reservations exceed 2 GiB. It may lead to memory corruption or denial-of-service conditions, especially in systems using large memory allocations like memblock reserve_mem.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it pertains to a specific kernel memory reservation issue rather than data protection or privacy controls.

Mitigation Strategies

Apply the latest kernel patches from your Linux distribution to ensure the fix for kho_preserved_memory_reserve() is included. If patches are unavailable, avoid using large memory reservations (>2 GiB) via kho_preserve_pages() until an update is applied.

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