CVE-2026-46065

Analyzed Analyzed - Analysis Complete

Deferred I/O Use-After-Free in Linux Kernel

Publication date: 2026-05-27

Last updated on: 2026-06-24

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info Hold state of deferred I/O in struct fb_deferred_io_state. Allocate an instance as part of initializing deferred I/O and remove it only after the final mapping has been closed. If the fb_info and the contained deferred I/O meanwhile goes away, clear struct fb_deferred_io_state.info to invalidate the mapping. Any access will then result in a SIGBUS signal. Fixes a long-standing problem, where a device hot-unplug happens while user space still has an active mapping of the graphics memory. The hot- unplug frees the instance of struct fb_info. Accessing the memory will operate on undefined state.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-05-27

Last Modified

2026-06-24

Generated

2026-07-06

AI Q&A

2026-05-27

EPSS Evaluated

2026-07-05

NVD

CVE-2026-46065

EUVD

EUVD-2026-32447

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	From 6.13 (inc) to 6.18.30 (exc)
linux	linux_kernel	From 6.7 (inc) to 6.12.88 (exc)
linux	linux_kernel	From 6.2 (inc) to 6.6.140 (exc)
linux	linux_kernel	From 6.19 (inc) to 7.0.4 (exc)
linux	linux_kernel	From 5.16 (inc) to 6.1.176 (exc)
linux	linux_kernel	From 2.6.22 (inc) to 5.15.210 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-401	The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Attack-Flow Graph

Executive Summary

This vulnerability exists in the Linux kernel's framebuffer device (fbdev) deferred I/O subsystem. It involves improper handling of the lifetime of the struct fb_info, which represents the framebuffer device information.

Specifically, when a device is hot-unplugged while user space still has an active memory mapping of the graphics memory, the struct fb_info instance is freed. However, user space may still access this memory, which leads to undefined behavior.

The fix involves holding the state of deferred I/O in a separate struct fb_deferred_io_state, allocating it during initialization, and only removing it after the final mapping is closed. If fb_info is freed earlier, the mapping is invalidated so that any access results in a SIGBUS signal, preventing undefined memory access.

Impact Analysis

This vulnerability can lead to undefined behavior or system instability if a device is hot-unplugged while user space still accesses the graphics memory mapping.

Specifically, accessing freed memory can cause crashes or data corruption in applications using the framebuffer device.

The fix ensures that such access results in a SIGBUS signal, which safely notifies the application of invalid memory access instead of causing unpredictable behavior.

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