CVE-2026-80823

What the bug is

st21nfca_tm_recv_atr_req() checks that the received ATR_REQ frame is at least ST21NFCA_ATR_REQ_MIN_SIZE and that the self-declared atr_req->length is at least sizeof(struct st21nfca_atr_req), but never checks that atr_req->length does not exceed the actual received length (skb->len). st21nfca_tm_send_atr_res() then trusts the declared length: gb_len = atr_req->length - sizeof(struct st21nfca_atr_req); ... memcpy(atr_res->gbi, atr_req->gbi, gb_len); so an RF peer that sends a short frame but sets atr_req->length larger than the frame makes gb_len exceed the general bytes actually present, and the memcpy reads out of bounds past the received skb. Those bytes are placed in the ATR_RES and sent back to the peer (kernel-memory disclosure to a proximity attacker); a larger declared length is an out-of-bounds read (DoS). Reject frames whose declared length exceeds the received length. The adjacent nfc_tm_activated() path in the same function already derives its general-bytes length from skb->len rather than the declared field. Found by 0sec (https://0sec.ai) using automated source analysis; the missing bound is evident from source. Compile-tested.

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/dep.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_hci, and Debian does not compile it into that module, so finding st21nfca_hci in lsmod would say nothing about this CVE.

Check it on the machine

grep -w CONFIG_NFC_ST21NFCA /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 5 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, sid, bookworm · linux-6.12n

n

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

Build switch

CONFIG_NFC_ST21NFCA

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

2026-09-04 (44 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.24%, higher than 14.4% of all CVEssource

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
3.17	5.10.267	785df00bb3ae
3.17	5.15.218	2c1ad291f4cd
3.17	6.1.185	dd26d30f40c4
3.17	6.6.154	9635507fe829
3.17	6.12.106	0f344944c506
3.17	6.18.47	bfcca5f42c9a
3.17	7.1.11	304f5b414f40
3.17	7.2.1	f33cecf69095
3.17	7.3	5cdcca5d62a6

Debian advisories