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CVE-2026-80601
batman-adv: gw: acquire ethernet header only after skb realloc
Published 2026-08-28 (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-2026-80601 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
The pskb_may_pull() called by batadv_get_vid() 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.
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/gateway_client.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.
- bookworm, trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- 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
- 2026-08-28 (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
- 0.40%, higher than 32.8% 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 |
|---|---|---|
| 3.14 | 5.10.261 | 2760b38222c8 |
| 3.14 | 5.15.212 | 6c37f1166549 |
| 3.14 | 6.1.178 | b79884a5567b |
| 3.14 | 6.6.145 | afac8096bde4 |
| 3.14 | 6.12.97 | e3f4325e35dd |
| 3.14 | 6.18.40 | e6b43acd34b2 |
| 3.14 | 7.1.5 | 916dac5f2944 |
| 3.14 | 7.2 | 77880a3be88d |
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
- The bug is hit only in batadv_interface_tx on outgoing bat0 traffic; the highest-impact path is an unauthenticated client on the same WiFi/LAN segment bridged to a batman-adv gateway node sending a crafted VLAN-tagged DHCP packet into bat0.
- AC:LAttack complexity, low
- Triggering is synchronous and attacker-controlled: a VLAN-tagged DHCP discover/request shaped to force pskb_may_pull() skb reallocation deterministically hits the stale ethhdr UAF without races or victim-specific timing.
- PR:NPrivileges required, none
- No privileges on the mesh router are required when a client on a bridged WiFi/LAN port injects the malicious DHCP frame; gateway-client mode is operator configuration, not an attacker privilege.
- UI:NUser interaction, none
- Exploitation requires no victim interaction beyond normal always-on mesh bridging and DHCP forwarding; the attacker only sends a malicious frame.
- S:UScope, unchanged
- Impact is kernel memory corruption and potential privilege escalation within the same kernel/host security boundary, not a cross-boundary escape such as VM or sandbox breakout.
- C:HConfidentiality impact, high
- This is a use-after-free read: after skb reallocation, ethhdr->h_source/h_dest dereference freed skb head memory, enabling uncontrolled kernel memory disclosure and further exploitation primitives.
- I:HIntegrity impact, high
- UAF on skb data can corrupt routing lookups (batadv_transtable_search) and adjacent kernel heap state, providing a standard path to controlled writes and arbitrary kernel code execution.
- A:HAvailability impact, high
- Reading freed skb memory via ethhdr commonly causes kernel oops/panic on the batman-adv gateway node, yielding complete loss of mesh connectivity and host availability.