CVE-2026-80742

What the bug is

syzbot reported a WARNING in __dev_queue_xmit() triggered via tpacket_snd(): skb_assert_len WARNING: at include/linux/skbuff.h:2753 skb_assert_len WARNING: at __dev_queue_xmit+0x21bc/0x4970 net/core/dev.c:4781 Call Trace: <TASK> dev_queue_xmit include/linux/netdevice.h:3448 [inline] packet_xmit+0x243/0x310 net/packet/af_packet.c:276 tpacket_snd net/packet/af_packet.c:2907 [inline] packet_sendmsg+0x28d6/0x4eb0 net/packet/af_packet.c:3134 When sending 0-byte packets via TPACKET ring buffer on devices with no hard header (e.g. dev->hard_header_len == 0), tpacket_fill_skb() populates an skb with skb->len == 0 and returns 0. tpacket_snd() then forwards this empty skb to packet_xmit(), causing __dev_queue_xmit() to hit skb_assert_len(skb). Similar checks exist in packet_snd() via commit dc633700f00f ("net/af_packet: check len when min_header_len equals to 0") and in packet_sendmsg_spkt() via commit 6a341729fb31 ("af_packet: Don't send zero-byte data in packet_sendmsg_spkt()."). Return -EINVAL in tpacket_fill_skb() when skb->len is zero to reject zero-length packets in tpacket_snd().

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.

net/packet/af_packet.c

What this is

PACKET SOCKETSMAINTAINERS section matched on net/packet/af_packet.c · Maintained

Check it on the machine

grep -w CONFIG_PACKET /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 builds this code. Every release below compiles the affected file into the kernels it ships.

• bookworm, trixie, forky, sid, bookworm · linux-6.12y

y

built into the kernel image on every flavour - only a patch removes it

Build switch

CONFIG_PACKET

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

2026-09-03 (2 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.18%, higher than 6.8% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

net/packet

Upstream fixes

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

Introduced	Fixed in	Commit
2.6.12	5.10.266	dde212f8622f
2.6.12	5.15.217	80a702964467
2.6.12	6.1.184	7521e691c7c4
2.6.12	6.6.153	1fc70b3d513b
2.6.12	6.12.105	3fa110f9e2ea
2.6.12	6.18.46	98c5914d6b7b
2.6.12	7.1.10	f09ac5682f1b
2.6.12	7.2	6bcd76c134c5

Debian advisories