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CVE-2026-68314
net: mctp i3c: clean up notifier and buses if driver register fails
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-68314 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 | fixed | 6.12.101-1 | Update the kernel and reboot. Fixed in 6.12.101-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
mctp_i3c_mod_init() registers the I3C bus notifier and then walks the existing buses with i3c_for_each_bus_locked(mctp_i3c_bus_add_new, NULL) before registering the I3C device driver. If i3c_driver_register() fails, the function returns the error directly, leaving the notifier registered and every mctp_i3c_bus object created for the existing buses allocated. The notifier is left pointing into the module that failed to load and the bus list is leaked. Mirror the module exit path on this failure: unregister the notifier and tear down the buses that were added before returning the error. This issue was identified during our ongoing static-analysis research while reviewing kernel code.
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/net/mctp/mctp-i3c.c
- What this is
- MANAGEMENT COMPONENT TRANSPORT PROTOCOL (MCTP)MAINTAINERS section matched on drivers/net/mctp/ · netdev@vger.kernel.org · Maintained
Check it on the machine
grep -wE 'CONFIG_MCTP|CONFIG_MCTP_TRANSPORT_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 4 releases. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixie, forky, sid, bookworm · linux-6.12n
- ?
- 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_MCTP, CONFIG_MCTP_TRANSPORT_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
- 2026-08-10 (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
- 0.13%, higher than 2.2% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.7 | 6.12.101 | 49d15cfab247 |
| 6.7 | 6.18.42 | a8bd8c109da5 |
| 6.7 | 7.1.6 | a40e83a34eaa |
| 6.7 | 7.2 | 03d1057305ef |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | 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 stale notifier and leftover mctpi3cN netdevs are reached from the local system — an AF_MCTP socket transmit or a local I3C bus hotplug event — not from any remote or adjacent network peer.
- AC:LAttack complexity, low
- Once module init has failed, the leftover state is deterministic and any local user can drive traffic into the freed module's netdev ops or wait for a bus event with no additional conditions to win.
- PR:LPrivileges required, low
- After the failed load leaves the interfaces registered, an ordinary unprivileged user can open an AF_MCTP socket and send on the stale mctpi3cN interface, dereferencing function pointers in freed module memory without any capability.
- UI:NUser interaction, none
- No victim action is needed; the leftover netdevs and notifier are globally visible and can be exercised directly by the attacker or by ordinary I3C bus events.
- S:UScope, unchanged
- The stale pointers and leaked objects are all kernel-side resources within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.
- C:HConfidentiality impact, high
- Execution against freed module text/data is a use-after-free of a region that can be reclaimed and shaped by the attacker, permitting disclosure of arbitrary kernel memory contents through the reused allocation.
- I:HIntegrity impact, high
- Calling through notifier_call and netdev_ops pointers residing in freed module memory yields control-flow hijack once that memory is reallocated, giving an arbitrary write / code execution primitive.
- A:HAvailability impact, high
- Even without successful reclamation, invoking the stale notifier or the leftover netdev's ops jumps into unmapped or reused memory and reliably oopses/panics the kernel; the leaked netdevs and kthread are also never freed.