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CVE-2026-80579
fbdev: clear fb_info->mode before deleting a videomode
Published 2026-08-26 (2 months ago) by the Linux kernel CNA. Subsystem drivers/video. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-80579 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
fb_set_var() can delete a mode from info->modelist when userspace passes FB_ACTIVATE_INV_MODE through FBIOPUT_VSCREENINFO. The code checks that the mode being deleted is not the current info->var and that fbcon is not using it, but it does not check fb_info->mode. fb_info->mode may still point into the modelist entry being deleted. If the entry is freed, later mode sysfs reads through show_mode() can dereference a stale pointer. Clear fb_info->mode before calling fb_delete_videomode() when it matches the mode being removed.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/video/fbdev/core/fbmem.c
- What this is
- FRAMEBUFFER COREMAINTAINERS section matched on drivers/video/fbdev/core/ · Odd Fixes
Check it on the machine
grep -wE 'CONFIG_FB|CONFIG_FB_CORE' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormy
- trixie, forky, sidYnot built on s390x/s390x
- y
- built into the kernel image on every flavour - only a patch removes it
- Y
- built in where it is built at all; some flavours do not build it
- Build switches
- CONFIG_FB, CONFIG_FB_CORE
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-26 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/video
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 7.1.10 | ce7fef961c63 |
| 2.6.12 | 7.2 | 95e647d2a530 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The bug is reached only through local framebuffer interfaces—FBIOPUT_VSCREENINFO ioctl on /dev/fb* to delete a videomode and sysfs reads of /sys/class/graphics/fb*/mode via show_mode(); fbdev core has no network, Bluetooth, or remote packet path.
- AC:LAttack complexity, low
- Exploitation is a deterministic state bug, not a race: ioctl with FB_ACTIVATE_INV_MODE frees the modelist kmalloc entry while fb_info->mode still points into it, and a subsequent sysfs mode read reliably dereferences the stale pointer without attacker-uncontrollable timing.
- PR:LPrivileges required, low
- The freeing trigger is FBIOPUT_VSCREENINFO on /dev/fb*, which requires only local framebuffer device access (video group or kiosk/embedded/HMI service accounts), not init-namespace root; sysfs mode reads are world-readable and complete the UAF disclosure path.
- UI:NUser interaction, none
- No victim interaction is required; the attacker performs ioctl mode deletion and sysfs mode reads through their own local process without needing another user to mount, open, or configure unrelated resources.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap state within the local fbdev subsystem and does not cross VM, container, or IOMMU boundaries to impact resources under a different security authority.
- C:HConfidentiality impact, high
- After fb_delete_videomode() kfree()s the fb_modelist object, show_mode()/mode_string() reads flag, vmode, xres, yres, and refresh from freed slab memory and copies attacker-influenced bytes to userspace—a UAF information-disclosure primitive.
- I:HIntegrity impact, high
- The dangling fb_info->mode pointer into a freed kmalloc object enables classic heap grooming between ioctl free and sysfs read; reallocated slab contents can be corrupted or confused for control-flow or arbitrary-write primitives beyond the immediate read.
- A:HAvailability impact, high
- Dereferencing the freed fb_videomode structure causes KASAN-detectable use-after-free faults and kernel oops/panic on display-equipped embedded, automotive, kiosk, and console systems running the framebuffer subsystem.