CVE-2026-98711

What the bug is

The TX path rounds the transfer size up to the bus alignment (align_size(), up to 511 bytes for SDIO, 1 byte for SPI) but sends the padded length straight from the frame buffer, which has no room reserved for the padding. cw1200_data_write() therefore reads past the end of the frame and the bus transfer carries those bytes to the device. A bogus device can collect up to 511 bytes of kernel heap data per TX frame. The RX path does not have this problem: it allocates the skb with the aligned length (alloc_len) before reading. Compute the exact padding with the bus align_size() callback, make sure queued TX frames have tailroom for it, and zero the padding bytes before the transfer so nothing past the frame is exposed. This is not expected to change driver behavior on most cases: frame contents and transfer sizes are unchanged, only the content of the padding bytes (previously undefined stale memory, now zero), which the device never reads since the WSM header carries the real frame length. The skb expansion can only fail under memory exhaustion, in which case the frame is dropped like on the existing error paths of cw1200_tx(). Discovered by Atuin - Automated Vulnerability Discovery Engine.

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/wireless/st/cw1200/bh.c
drivers/net/wireless/st/cw1200/txrx.c

What this is

CW1200 WLAN driverMAINTAINERS section matched on drivers/net/wireless/st/ · linux-wireless@vger.kernel.org · Orphan

Kernel module

none to look for. The file would have gone into cw1200_core, and Debian does not compile it into that module, so finding cw1200_core in lsmod would say nothing about this CVE.

Check it on the machine

grep -wE 'CONFIG_CW1200|CONFIG_WLAN|CONFIG_WLAN_VENDOR_ST' /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 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, sidn

n

not enabled on any flavour - this release does not build the code

Build switches

CONFIG_CW1200, CONFIG_WLAN, CONFIG_WLAN_VENDOR_ST

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

2026-10-18 (today)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

not scored

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

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
3.11	6.12.113	71f693a0eccc
3.11	6.18.56	b0e97bd40e0c
3.11	7.2.10	678c8f4ba285
3.11	7.3	7c1611780823