CVE-2026-68368

What the bug is

When unpacking host-supplied NTBs, ncm_unwrap_ntb() checks datagram length against frame_max but does not verify that the datagram fits within the declared block length. Additionally, when decoding multiple NTBs from a single socket buffer, subsequent block lengths are not checked against the actual remaining buffer data. With these checks missing, a malicious USB host can specify datagram offsets and lengths that point beyond the block, or supply secondary NTB headers declaring lengths larger than the buffer. skb_put_data() then copies adjacent kernel memory from skb_shared_info into the network skb. Fix this by verifying that sufficient buffer space remains for the NTB header before parsing, handling zero-length block declarations, ensuring that block lengths never exceed the remaining buffer space, and verifying that each datagram payload stays strictly within the block boundary.

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/usb/gadget/function/f_ncm.c

What this is

USB SUBSYSTEMMAINTAINERS section matched on drivers/usb/ · linux-usb@vger.kernel.org · Supported

Kernel module

usb_f_ncm

Check it on the machine

grep -wE 'CONFIG_OF|CONFIG_PCI|CONFIG_USB|CONFIG_USB_F_NCM|CONFIG_USB_GADGET|CONFIG_USB_PHY|CONFIG_USB_SUPPORT' /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.

lsmod | grep -w usb_f_ncm

Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.

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.

• bookwormMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
• trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armel/rpi, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
• forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
• bookworm · linux-6.12Mnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k

M

a module where it is built at all; some flavours do not build it

Build switches

CONFIG_OF, CONFIG_PCI, CONFIG_USB, CONFIG_USB_F_NCM, CONFIG_USB_GADGET, CONFIG_USB_PHY, CONFIG_USB_SUPPORT

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

no vector published, unrated

Attack vector

not published

EPSS

0.22%, higher than 11.2% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

drivers/usb

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
5.9	5.10.265	35d15bbaec05
5.9	5.15.216	6b2be489eaa6
5.9	6.1.183	f87ed889f0f7
5.9	6.6.148	e07751d0527c
5.9	6.12.101	fff1059d139e
5.9	6.18.42	40c706a0224b
5.9	7.1.6	41fd5f2fb002
5.9	7.2	1febec7e47cd
4.9.235	0	0
4.14.196	0	0
4.19.143	0	0
5.4.62	0	0
5.8.6	0	0
4.14.328	0	0
4.19.297	0	0
5.4.259	0	0

Debian advisories