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CVE-2026-80950
i3c: renesas: Check that the transfer is valid before accessing it
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/i3c. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80950 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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. |
The vulnerability
What the bug is
The Renesas I3C driver uses an asynchronous model to transfer data. It prepares a struct renesas_i3c_xfer, enqueues it, and waits for completion. The interrupt handler dequeues the transfer, updates/uses it, and signals the waiting thread. If the completion times out, the waiting thread dequeues the transfer and free it. If an interrupt fires after that, the handler may access freed memory, leading to crashes. Check that the transfer is still valid before accessing it in the interrupt handler. With it clear any status flags and disable all the interrupts to avoid triggering the same interrupts again.
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/renesas-i3c.c
- What this is
- I3C DRIVER FOR RENESASMAINTAINERS section matched on drivers/i3c/master/renesas-i3c.c · Supported
Check it on the machine
grep -wE 'CONFIG_I3C|CONFIG_RENESAS_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 2 releases. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidn
- ?
- not established - no Makefile entry for the affected file
- n
- not enabled on any flavour - this release does not build the code
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switches
- CONFIG_I3C, CONFIG_RENESAS_I3C
- 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
- 2026-09-11 (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
- 0.17%, higher than 6.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- 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 |
|---|---|---|
| 6.17 | 6.18.50 | 0093f9fc102b |
| 6.17 | 7.2.4 | ec631aff9326 |
| 6.17 | 7.3 | 5f1a76ecfe90 |
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 UAF is reached from local I3C/I2C transfer paths on Renesas RZ SoCs: i2c-dev I2C_RDWR/I2C_TIMEOUT on the I3C master's I2C adapter, I3C client sysfs (IIO/hwmon) private transfers, and the master's do_daa sysfs. No network protocol delivers data into this driver.
- AC:LAttack complexity, low
- A local attacker can start a transfer and force the software completion timeout (hardcoded 1s on I3C, or attacker-set via I2C_TIMEOUT including 0) so the waiter dequeues and frees the xfer while controller IRQs remain armed; the later ISR then uses the stale object, and the attacker can retry at will.
- PR:LPrivileges required, low
- i2cdev_open() has no capability check; reachability depends on /dev/i2c-* DAC (commonly 0660 root:i2c on embedded and automotive boards) or unprivileged reads of I3C-backed IIO/hwmon sysfs. That is ordinary local access, not init-namespace root.
- UI:NUser interaction, none
- The attacker issues their own open/ioctl or sysfs operations against already-present I3C/I2C interfaces; no separate victim action such as plugging a device or mounting a filesystem is required.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap state in the I3C master driver within the same kernel security authority and does not cross a VM, IOMMU, or sandbox boundary.
- C:HConfidentiality impact, high
- After timeout the ISR dereferences the freed renesas_i3c_xfer (including cmds, buffers, and completion). Reclaiming that kmalloc object lets an attacker control what the IRQ path reads from kernel memory, which per UAF guidance is High confidentiality impact.
- I:HIntegrity impact, high
- The IRQ handlers write through the freed xfer (xfer->ret, complete(&xfer->comp), FIFO copies into cmd->rx_buf). A sprayed fake object can turn cmd->rx_buf into an arbitrary kernel write and hijack control flow, so integrity impact is High.
- A:HAvailability impact, high
- Even without exploitation, the post-timeout ISR dereferences a NULL or freed transfer pointer in hardirq context, causing a kernel oops or panic and full loss of availability.