CVE-2026-98582

What the bug is

st21nfca_hci_i2c_repack() trims a received frame at its EOF marker before removing byte stuffing. It then assumes the truncated frame contains the LLC header and two CRC bytes, and it unconditionally reads the byte after an escape marker. A malformed frame can place EOF immediately after the start marker or can end its data portion with an escape marker. The former leaves too few bytes for check_crc(), while the latter makes the unstuffing loop read past the current skb length. Require the minimum framing bytes both before and after unstuffing. Use separate input and output cursors while removing byte stuffing, and reject an escape marker without its encoded byte. This keeps malformed frames within the received frame boundary before CRC processing.

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/nfc/st21nfca/i2c.c

What this is

NFC SUBSYSTEMMAINTAINERS section matched on drivers/nfc/ · oe-linux-nfc@lists.linux.dev · Maintained

Kernel module

none to look for. The file would have gone into st21nfca_i2c, and Debian does not compile it into that module, so finding st21nfca_i2c in lsmod would say nothing about this CVE.

Check it on the machine

grep -wE 'CONFIG_NFC_ST21NFCA|CONFIG_NFC_ST21NFCA_I2C' /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_NFC_ST21NFCA, CONFIG_NFC_ST21NFCA_I2C

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/nfc

Upstream fixes

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

Introduced	Fixed in	Commit
3.16	5.10.271	8934d2889ae1
3.16	5.15.222	d0596ee6c4b9
3.16	6.1.189	f526c218a149
3.16	6.6.158	d4008c3499db
3.16	6.12.112	91be5161f37b
3.16	6.18.55	57919d0662d8
3.16	7.2.9	7b996cc06dda
3.16	7.3	a653c01ce447