CVE-2026-89780

What the bug is

rmnet_map_deaggregate() allocates each sub-frame with alloc_skb() and leaves skb->dev NULL. __rmnet_map_ingress_handler() assigns skb->dev = ep->egress_dev only on the data path, but a MAP command frame is dispatched to rmnet_map_command() before that, so rmnet_map_send_ack() runs netif_tx_lock(skb->dev) on a NULL device. An unprivileged user reaches this by unsharing a user+net namespace, creating an rmnet link over a tap device with INGRESS_DEAGGREGATION and INGRESS_MAP_COMMANDS, and writing an aggregated frame carrying a flow-control command to the tap fd. Restore the assignment dropped by 378e25357ac7, so every skb leaving rmnet_map_deaggregate() has a valid device. BUG: KASAN: null-ptr-deref in _raw_spin_lock (kernel/locking/spinlock.c:158) Write of size 4 at addr 00000000000004b4 by task exploit/144 Call Trace: _raw_spin_lock (kernel/locking/spinlock.c:158) netif_tx_lock (net/sched/sch_generic.c:497) rmnet_map_command (drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c:67) rmnet_rx_handler (drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c:125) __netif_receive_skb_core.constprop.0 (net/core/dev.c:6103) ... __netif_receive_skb_one_core (net/core/dev.c:6214) netif_receive_skb (net/core/dev.c:6474) tun_get_user (drivers/net/tun.c:1966) tun_chr_write_iter (drivers/net/tun.c:2012) vfs_write (fs/read_write.c:687) ksys_write (fs/read_write.c:739) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Kernel panic - not syncing: Fatal exception in interrupt

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/ethernet/qualcomm/rmnet/rmnet_map_data.c

What this is

QUALCOMM RMNET DRIVERMAINTAINERS section matched on drivers/net/ethernet/qualcomm/rmnet/ · netdev@vger.kernel.org · Maintained

Kernel module

rmnet

Check it on the machine

grep -wE 'CONFIG_ETHERNET|CONFIG_NET_VENDOR_QUALCOMM|CONFIG_RMNET' /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 rmnet

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 does not build this code in 3 releases. It does build it in 2 releases, so the answer depends on which release the machine runs.

• bookworm, trixien
• forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
• bookworm · linux-6.12n

n

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

M

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

Build switches

CONFIG_ETHERNET, CONFIG_NET_VENDOR_QUALCOMM, CONFIG_RMNET

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

2026-09-16 (33 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.22%, higher than 11.3% of all CVEssource

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
4.17	5.10.270	5aaa7409c1b4
4.17	5.15.221	9b78ab84ddf9
4.17	6.1.188	9d18c6c6cd16
4.17	6.6.157	4bcef54e4a33
4.17	6.12.110	b14c22c31d9e
4.17	6.18.52	7abe769e72c7
4.17	7.2.6	200460a0793d
4.17	7.3	a66734a1c5e3

Debian advisories