CVE-2026-97604 fbdev: vfb: defer cleanup until the last reference
A use-after-free in the Linux kernel's virtual framebuffer driver allows local attackers to execute code or escalate privileges via race conditions during device unbinding.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-97604?
CVE-2026-97604 is an use after free vulnerability in Linux, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
fbdev: vfb: defer cleanup until the last reference
FBIOGETCMAP takes a shallow snapshot of info->cmap and performs the usercopy after dropping info->lock. vfb_remove() frees the colormap immediately after unregistering the framebuffer, even when an open file still holds a reference to fb_info. A concurrent driver unbind can therefore free the colormap while the ioctl copies it to userspace.
KASAN reports:
BUG: KASAN: slab-use-after-free in _copy_to_user Read of size 512 by task poc/125
_copy_to_user (./include/linux/instrumented.h:129 ./include/linux/uaccess.h:201 lib/usercopy.c:24) fb_cmap_to_user (./include/linux/uaccess.h:230 drivers/video/fbdev/core/fbcmap.c:211) do_fb_ioctl (drivers/video/fbdev/core/fb_chrdev.c:114)
Allocated by task 1: fb_alloc_cmap_gfp (./include/linux/slab.h:973 ./include/linux/slab.h:1290 drivers/video/fbdev/core/fbcmap.c:108) vfb_probe (drivers/video/fbdev/vfb.c:459)
Freed by task 124: fb_dealloc_cmap (drivers/video/fbdev/core/fbcmap.c:151) vfb_remove (drivers/video/fbdev/vfb.c:489)
unregister_framebuffer() drops the registration reference, and fbdev calls fb_destroy after the last put_fb_info(). Move the registered framebuffer's cleanup into an fb_destroy callback so its colormap and screen buffer stay alive until all file references have been released.
Which versions are affected by CVE-2026-97604?
How do I fix CVE-2026-97604?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-97604 being exploited?
There is no known exploitation of CVE-2026-97604 in the wild and no public exploit code.
Sources
Also known as AZL-104466, BELL-CVE-2026-97604, DEBIAN-CVE-2026-97604, GHSA-8fh7-qq2h-xhh6, UBUNTU-CVE-2026-97604.