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CVE-2026-72232
batman-adv: ensure minimal ethernet header on TX
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-2026-72232 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
As documented in commit 8bd67ebb50c0 ("net: bridge: xmit: make sure we have at least eth header len bytes"), it is possible by for a local user with eBPF TC hook access to attach a tc filter which truncates the packet and redirects to an batadv interface. But the code assumes that at least ETH_HLEN bytes are available and thus might read outside of the available buffer. The batadv_interface_tx() must therefore always check itself if enough data is available for the ethernet header and don't rely on min_header_len.
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_advPrints 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
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 4.3% 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 | 58799078afeb |
| 2.6.38 | 5.15.212 | 38cd10b0aeec |
| 2.6.38 | 6.1.178 | 811fea37620f |
| 2.6.38 | 6.6.145 | e6640923afee |
| 2.6.38 | 6.12.97 | 6b4f521e0125 |
| 2.6.38 | 6.18.40 | 9e16b6751a82 |
| 2.6.38 | 7.1.5 | dbeb4145d977 |
| 2.6.38 | 7.2 | 49df66b7993c |
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:LAttack vector, local
- Reachable only via local ndo_start_xmit on a batadv netdev after a TC/eBPF program (bpf_redirect/bpf_clone_redirect or mirred) truncates an skb below ETH_HLEN; there is no credible remote or adjacent path without local TC/BPF control.
- AC:LAttack complexity, low
- An attacker with CAP_NET_ADMIN can reliably attach a TC clsact filter, shrink the skb (e.g. bpf_skb_adjust_room), and redirect to bat0; no race or victim state beyond attacker-controlled namespace setup is required.
- PR:LPrivileges required, low
- Exploitation requires CAP_NET_ADMIN to attach TC/BPF programs and create/use a batadv interface; this capability is obtainable by unprivileged users inside user/network namespaces (unshare -Urn), not only init-namespace root.
- UI:NUser interaction, none
- No victim interaction is needed; the attacker triggers the bug by installing the TC filter and transmitting or test-running the crafted skb themselves.
- S:UScope, unchanged
- Impact remains within the kernel/network stack security authority (memory disclosure, mesh state corruption, crash); it does not by itself cross a VM, container, or IOMMU boundary.
- C:HConfidentiality impact, high
- Missing ETH_HLEN validation causes an out-of-bounds read of up to 12 bytes past skb->tail via eth_hdr(), exposing adjacent slab/uninitialized kernel memory and enabling heap grooming for further exploitation.
- I:HIntegrity impact, high
- OOB-read ethernet header fields drive batadv_tt_local_add, DAT/ARP snooping, and mesh forwarding decisions, corrupting translation/routing state; kernel OOB reads are also commonly chained into arbitrary write primitives.
- A:HAvailability impact, high
- Reading beyond the skb buffer can trigger kernel oops/panic (as seen in the analogous bridge/bpf_redirect syzbot reports) and enables repeated, attacker-controlled crashes on mesh nodes running batman-adv.