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CVE-2026-80952
i3c: master: Fix info leak and UAF in device unregister path
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/i3c. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-80952 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 | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
i3c_master_unregister_i3c_devs() clears i3cdev->dev->desc before calling device_unregister(). During device_unregister(), device_del() emits a KOBJ_REMOVE uevent and unbinds the driver while the device descriptor is still expected to be valid. As a result, i3c_device_uevent() and a racing modalias_show() can observe a NULL desc and fall back to an uninitialized stack struct i3c_device_info, leaking kernel stack contents in the generated modalias. Driver .remove() callbacks may also encounter an unexpected NULL desc during unbind. Keep desc valid until device_unregister() has completed. Since device_unregister() drops the device reference and may free the device, take an extra reference with get_device() before unregistering. Clear desc afterwards and release the extra reference with put_device(). This preserves the release-time invariant that desc must be NULL while avoiding both the information leak and a potential use-after-free from writing desc after the device has been released.
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/i3c/master.c
- What this is
- I3C SUBSYSTEMMAINTAINERS section matched on drivers/i3c/ · linux-i3c@lists.infradead.org · Maintained
- Kernel module
- none to look for. The file would have gone into i3c, and Debian does not compile it into that module, so finding i3c in lsmod would say nothing about this CVE.
Check it on the machine
grep -w CONFIG_I3C /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 does not build this code. In 5 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sid, bookworm · linux-6.12n
- n
- not enabled on any flavour - this release does not build the code
- Build switch
- CONFIG_I3C
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
- 2026-09-11 (37 days 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
- 0.13%, higher than 2.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/i3c
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.0 | 5.10.270 | 334cfb5e285c |
| 5.0 | 5.15.221 | 109995153898 |
| 5.0 | 6.1.188 | c64daaaba08e |
| 5.0 | 6.6.157 | ef72ff6650c4 |
| 5.0 | 6.12.109 | c16b6f25e0cc |
| 5.0 | 6.18.50 | 94fb9786d67a |
| 5.0 | 7.2.4 | 4837be0f9ac2 |
| 5.0 | 7.3 | d2c743efd2d1 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
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 in i3c_master_unregister_i3c_devs(), reached only from I3C master platform/PCI driver .remove() (sysfs unbind, rmmod, or controller teardown). No network, Bluetooth, or remote packet path enters this unregister sequence.
- AC:LAttack complexity, low
- Clearing desc before device_unregister() deterministically poisons KOBJ_REMOVE uevent/modalias, and the later device free races with in-flight IBI work still holding desc->dev. An attacker looping bind/unbind while sensors generate IBIs or while reading sysfs modalias controls both sides of the race.
- PR:LPrivileges required, low
- Per CNA driver-removal UAF precedent (including CVE-2024-49874 on this same i3c_master_unregister path), an unprivileged local user can drive the IBI/sysfs side via world-readable I3C modalias and IIO/hwmon/MCTP clients while teardown proceeds; init-namespace root is not the minimum privilege bar.
- UI:NUser interaction, none
- No separate victim action is required; the attacker reads sysfs/uevents and/or sustains I3C IBI traffic themselves and piggybacks on driver removal without another user opening files or mounting filesystems.
- S:UScope, unchanged
- Impact is kernel heap use-after-free and stack disclosure within the host kernel. This is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.
- C:HConfidentiality impact, high
- i3c_device_uevent() and a racing modalias_show() leak uninitialized kernel stack into MODALIAS when desc is NULL. After device_unregister() drops the last reference, i3c_master_handle_ibi() can invoke the IBI handler with a freed i3c_device, a heap UAF that enables arbitrary kernel read.
- I:HIntegrity impact, high
- In-flight i3c_master_handle_ibi() still calls ibi->handler() on the dangling i3c_device after it is freed, and driver .remove() may skip i3c_device_disable_ibi() because desc was already cleared. Heap reuse of that object yields write and control-flow hijack primitives.
- A:HAvailability impact, high
- Use-after-free of the i3c_device during unregister, and unexpected NULL desc in driver .remove() callbacks, can oops or panic the kernel even when the UAF is not fully exploited for code execution.