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CVE-2026-72235

batman-adv: retrieve ethhdr after potential skb realloc on RX

8.8 EPSS 0.3% AV:A

Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/batman-adv. Debian urgency: not yet assigned.

What to do, per Debian release

Debian's own status for CVE-2026-72235 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	fixed	6.1.180-1	Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts.
Debian 13trixie	fixed	6.12.100-1	Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts.
Debian 14forky	fixed	7.1.5-1	Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts.
Debian unstablesid	fixed	7.1.5-1	Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts.

The vulnerability

What the bug is

pskb_may_pull() in batadv_interface_rx() could reallocate the buffer behind the skb. Variables which were pointing to the old buffer need to be reassigned to avoid an use-after-free. This was done correctly for the VLAN header but missed for the ethernet header which is later used for the TT and AP isolation handling.

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/batman-adv/mesh-interface.c

What this is: BATMAN ADVANCEDMAINTAINERS section matched on net/batman-adv/ · b.a.t.m.a.n@lists.open-mesh.org · Maintained
Kernel module: batman_adv

Check it on the machine

grep -w CONFIG_BATMAN_ADV /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 batman_adv

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. The build rule could not be established for 2 releases, so nothing is claimed about those.

bookworm, trixie?
forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64

?: not established - no Makefile entry for the affected file
M: a module where it is built at all; some flavours do not build it

Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.

Build switch: CONFIG_BATMAN_ADV

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: 2026-08-15 (2 months ago)source
CVSS: 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it
Attack vector: adjacent network (AV:A)source
EPSS: 0.34%, higher than 26.4% of all CVEssource
CISA KEV: not listedthe KEV catalogue
Debian urgency: not yet assignedsource
Subsystem: net/batman-adv

Upstream fixes

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

Introduced	Fixed in	Commit
2.6.38	5.10.261	6e189f14d1ea
2.6.38	5.15.212	a1820344b180
2.6.38	6.1.178	6abf73589bed
2.6.38	6.6.145	f19259395b44
2.6.38	6.12.97	2cefa5141cab
2.6.38	6.18.40	85a71a81854e
2.6.38	7.1.5	b031fc97e199
2.6.38	7.2	035e1fed892d

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:AAttack vector, adjacent network: Exploitation requires delivering crafted ETH_P_BATMAN frames on the victim's batman-adv mesh hard interface (802.11/wired L2 mesh), reachable from any adjacent mesh peer without local shell access.
AC:LAttack complexity, low: The attacker fully controls remote batman-adv packet contents (VLAN-encapsulated payload and skb layout) and can repeatedly send unicast/broadcast frames to reliably force pskb_may_pull() skb reallocation.
PR:NPrivileges required, none: No privileges on the victim are required; any unauthenticated remote mesh participant that can inject batman-adv RX frames onto an active mesh node can reach batadv_interface_rx().
UI:NUser interaction, none: Exploitation is triggered solely by the attacker sending malicious mesh packets; no victim user action (mounting, clicking, or configuration changes) is needed at exploit time.
S:UScope, unchanged: Impact is kernel memory corruption and potential privilege escalation on the mesh node; it does not cross a VM/host, IOMMU, or sandbox security boundary.
C:HConfidentiality impact, high: Stale ethhdr after skb realloc is a use-after-free read of freed skb data; attacker-influenced bytes from ethhdr->h_source/h_dest are consumed by TT and AP-isolation logic, enabling arbitrary kernel memory disclosure.
I:HIntegrity impact, high: UAF-supplied MAC data is copied into translation-table heap objects via batadv_tt_add_temporary_global_entry()/batadv_tt_global_add(), providing a memory-corruption primitive suitable for control-flow or data hijacking.
A:HAvailability impact, high: Use-after-free on the RX path can cause kernel oops/panic from dereferencing freed skb buffer memory during TT/AP-isolation handling, even before full exploitation.