CVE-2026-74424
Received Received - Intake

NULL Pointer Dereference in Linux Kernel Framebuffer Console

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: fbcon: fix NULL pointer dereference for a console without vc_data fbcon_new_modelist() runs when a framebuffer's modelist changes. For each console mapped to it with fb_display[i].mode set, it reads vc_cons[i].d and passes the vc_num to fbcon_set_disp(). This assumes a console with a mode set has a vc_data, but it can be NULL. fbcon_set_disp() sets fb_display[i].mode before it checks vc_data, and fbcon_deinit() leaves the mode set after the vc_data is freed. fbcon_new_modelist() then dereferences the NULL vc_data. Keep fb_display[i].mode set only while the console has a vc_data. Check vc_data before setting the mode in fbcon_set_disp(), and clear the mode in fbcon_deinit(). The existing mode check in fbcon_new_modelist() then skips such consoles.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
CVE-2026-74424
EUVD
EUVD-2026-59571

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is a NULL pointer dereference in the Linux kernel's framebuffer console (fbcon) subsystem. It occurs when fbcon_new_modelist() tries to access vc_data for a console that has no allocated virtual console data. The issue arises because fbcon_set_disp() sets the display mode before checking if vc_data exists, and fbcon_deinit() fails to clear the mode after freeing vc_data.

Detection Guidance

This vulnerability is specific to the Linux kernel's framebuffer console (fbcon) subsystem. Detection requires checking the kernel version and fbcon module behavior. Inspect kernel logs for NULL pointer dereference errors related to fbcon or vc_data. Commands like 'dmesg | grep -i fbcon' or 'journalctl -k | grep -i NULL' may help identify crashes or errors.

Impact Analysis

This vulnerability could cause a system crash or kernel panic if exploited, leading to denial of service. It affects systems using framebuffer consoles, potentially causing instability or requiring a reboot to recover.

Mitigation Strategies

Update the Linux kernel to a patched version where this issue is resolved. If immediate patching is not possible, disable the framebuffer console (fbcon) by adding 'fbcon=map:0' to kernel boot parameters or blacklisting the fbcon module. Monitor system stability after changes.

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