CVE-2026-53403

Received Received - Intake

Null Pointer Dereference in Linux Kernel Framebuffer

Publication date: 2026-07-19

Last updated on: 2026-07-20

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: fbdev: Fix fb_new_modelist to prevent null-ptr-deref in fb_videomode_to_var info->var, a framebuffer's current mode, is expected to have a matching entry in info->modelist. var_to_display() relies on this and treats a failed fb_match_mode() as "This should not happen". fb_set_var() keeps it true by adding the mode to the list on every change, and do_register_framebuffer() does the same at registration. store_modes() replaces the modelist from userspace. fb_new_modelist() validates the new modes but does not check that info->var still has a match. It relies on fbcon_new_modelist() to re-point consoles, but that only handles consoles mapped to the framebuffer. With fbcon unbound there are none, so info->var is left describing a mode that is no longer in the list. A later console takeover runs var_to_display(), where fb_match_mode() returns NULL and leaves fb_display[i].mode NULL. fbcon_switch() passes it to display_to_var(), and fb_videomode_to_var() dereferences the NULL mode. Keep the current mode in the list in fb_new_modelist(), the same way fb_set_var() does.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-07-19

Last Modified

2026-07-20

Generated

2026-07-20

AI Q&A

2026-07-19

EPSS Evaluated

N/A

NVD

CVE-2026-53403

EUVD

EUVD-2026-45458

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 is a null-pointer dereference vulnerability in the Linux kernel's framebuffer subsystem. It occurs when the framebuffer's current mode is not properly maintained in the modelist after a mode change from userspace. This can lead to a NULL pointer being passed to functions that expect a valid mode, causing a crash.

Detection Guidance

This vulnerability is specific to the Linux kernel's framebuffer subsystem and requires kernel-level access to detect. Check if your kernel version is affected by running: uname -a. If the kernel version matches the vulnerable code path, further inspection of framebuffer modes and modelist consistency is needed via kernel debugging tools.

Impact Analysis

If exploited, this vulnerability could cause a system crash or kernel panic, leading to denial of service. It may also allow local attackers to escalate privileges or execute arbitrary code in the kernel context.

Compliance Impact

This vulnerability is a null-pointer dereference in the Linux kernel's framebuffer subsystem. It does not directly relate to data privacy, access control, or audit logging requirements in standards like GDPR or HIPAA. Compliance impact would depend on whether the affected system processes or stores regulated data, but the vulnerability itself is not a direct violation of these standards.

Mitigation Strategies

Update the Linux kernel to the latest stable version where this vulnerability is patched. If immediate patching is not possible, avoid unbinding fbcon from the framebuffer to prevent the null pointer dereference scenario described in the vulnerability.

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