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CVE-2026-63972

net: mana: Skip redundant detach on already-detached port

7.5 EPSS 0.6% AV:N

Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.

What to do, per Debian release

Debian's own status for CVE-2026-63972 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source

Release	Status	Version	What this means
Debian 12bookworm	not affected	6.1.190-1	Nothing to do. bookworm never shipped the vulnerable code.
Debian 13trixie	not affected	6.12.113-1	Nothing to do. trixie never shipped the vulnerable code.
Debian 14forky	fixed	7.0.12-1	Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts.
Debian unstablesid	fixed	7.0.12-1	Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts.

The vulnerability

What the bug is

When mana_per_port_queue_reset_work_handler() runs after a previous detach succeeded but attach failed, the port is left in a detached state with apc->tx_qp and apc->rxqs already freed. Calling mana_detach() again unconditionally leads to NULL pointer dereferences during queue teardown. Add an early exit in mana_detach() when the port is already in detached state (!netif_device_present) for non-close callers, making it safe to call idempotently. This allows the queue reset handler and other recovery paths to simply retry mana_attach() without redundant teardown.

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/microsoft/mana/mana_en.c

What this is: Hyper-V/Azure CORE AND DRIVERSMAINTAINERS section matched on drivers/net/ethernet/microsoft/ · linux-hyperv@vger.kernel.org · Supported
Kernel module: mana

Check it on the machine

grep -wE 'CONFIG_ETHERNET|CONFIG_MICROSOFT_MANA|CONFIG_NET_VENDOR_MICROSOFT' /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 mana

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 builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.

bookwormMnot built on armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
trixieMnot built on armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
forky, sidMnot built on armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x

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

Build switches: CONFIG_ETHERNET, CONFIG_MICROSOFT_MANA, CONFIG_NET_VENDOR_MICROSOFT
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

Debian tracker CVE record NVD kernel CNA record

Signals

Published: 2026-07-19 (3 months ago)source
CVSS: 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it
Attack vector: network (AV:N)source
EPSS: 0.59%, higher than 47.2% of all CVEssource
CISA KEV: not listedthe KEV catalogue
Debian urgency: unimportantsource
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
6.18.33	6.18.35	c4152b4e28b3
7.0	7.0.12	7ae590797f9b
7.0	7.1	5b05aa36ee24

Why the CNA scored it this way

Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source

AV:NAttack vector, network: The primary path is mana_tx_timeout() on Azure MANA NICs, triggered by the netdev TX watchdog when queues stall; remote peers on internet-facing VMs can induce TX stalls that schedule the vulnerable mana_detach() recovery workqueue.
AC:LAttack complexity, low: An attacker can repeatedly provoke TX watchdog timeouts and control retry timing; while attach failure between cycles may need memory pressure, remote connection floods can contribute and the attacker controls both sides of the reset race.
PR:NPrivileges required, none: The TX-timeout recovery path requires no local VM privileges—only network reachability to influence the victim's MANA interface TX queue behavior and trigger automated driver recovery.
UI:NUser interaction, none: Exploitation is fully automated through the kernel netdev watchdog timer and workqueue handler with no victim user interaction required.
S:UScope, unchanged: Impact is a kernel panic within the same Azure VM guest; the MANA driver runs in guest context and does not cross a VM/host security boundary.
C:NConfidentiality impact, none: The bug is a NULL pointer dereference during redundant queue teardown on already-freed pointers, causing a crash with no information disclosure primitive.
I:NIntegrity impact, none: There is no data modification or exploitable write primitive; the failure mode is dereferencing NULL tx_qp/rxqs pointers during teardown.
A:HAvailability impact, high: The NULL pointer dereference in mana_detach()/mana_dealloc_queues() causes a kernel oops/panic, fully disrupting VM availability on affected Azure instances.