CVE-2026-63826

What it is

In the Linux kernel, the following vulnerability has been resolved: fbdev: fix use-after-free in store_modes() store_modes() replaces a framebuffer's modelist with modes from userspace. On success it frees the old modelist with fb_destroy_modelist(). Two fields still point into that freed list. One pointer is fb_display[i].mode, the mode a console is using. fbcon_new_modelist() moves these pointers to the new list. It only does so for consoles still mapped to the framebuffer. An unmapped console is skipped and keeps its stale pointer. Unbinding fbcon, for example, sets con2fb_map[i] to -1 but leaves fb_display[i].mode set. An FBIOPUT_VSCREENINFO ioctl with FB_ACTIVATE_INV_MODE later reaches fbcon_mode_deleted(). That function reads the stale fb_display[i].mode through fb_mode_is_equal(). The read is a use-after-free. The other pointer is fb_info->mode, the current mode. It is set through the mode sysfs attribute. store_modes() does not update fb_info->mode, so it is left pointing into the freed list. show_mode(), the attribute's read handler, dereferences the stale fb_info->mode through mode_string(). The read is a use-after-free. Clear both pointers before freeing the list. Commit a1f305893074 ("fbcon: Set fb_display[i]->mode to NULL when the mode is released") added the helper fbcon_delete_modelist(). It clears every fb_display[i].mode that points into a given list. So far it is called only from the unregister path. Call it from store_modes() too, and set fb_info->mode to NULL.

At a glance

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2026-07-19 12:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-11-06 17:18 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: not scored yet.
• Fix: none linked yet, which raises it.

Details

Published

2026-07-19 12:16 UTC

Last modified

2026-11-06 17:18 UTC

Exploit probability

0.2% · EPSS, next 30 days

Record status

Awaiting Analysis

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