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CVE-2026-80600
batman-adv: dat: acquire ARP hw source 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-2026-80600 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/distributed-arp-table.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 -wE 'CONFIG_BATMAN_ADV|CONFIG_BATMAN_ADV_DAT' /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 switches
- CONFIG_BATMAN_ADV, CONFIG_BATMAN_ADV_DAT
- 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
- 2026-08-28 (2 months ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.73%, higher than 53.5% 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 |
|---|---|---|
| 5.1 | 5.10.261 | a82fc217cb7a |
| 5.1 | 5.15.212 | 86aa79b43e5b |
| 5.1 | 6.1.178 | d755cd001fa2 |
| 5.1 | 6.6.145 | 3404be97b940 |
| 5.1 | 6.12.97 | 01678c53a771 |
| 5.1 | 6.18.40 | 3b4c70c40f2e |
| 5.1 | 7.1.5 | 059a70e1d12d |
| 5.1 | 7.2 | 48067b2ae450 |
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
- Triggered when batadv_batman_skb_recv() processes remote batman-adv unicast/broadcast ETH_P_BATMAN frames on an active mesh hard interface; crafted VLAN-tagged embedded DHCPACK payloads reach batadv_dat_snoop_incoming_dhcp_ack() over the mesh network without local victim access.
- AC:LAttack complexity, low
- The attacker fully controls skb layout (batman header, 802.1Q tag, valid DHCPACK fields) to pass batadv_dat_check_dhcp_ack() and force batadv_dat_get_vid()->pskb_may_pull() skb reallocation before stale hw_src use; repeatable with no victim-timed race.
- PR:NPrivileges required, none
- No privileges on the victim host are required; any unauthenticated mesh peer (or L2 source able to inject ETH_P_BATMAN frames onto an active batman-adv hard interface with DAT enabled) can drive batadv_recv_unicast_packet()/batadv_recv_bcast_packet() without local login or CAP_NET_ADMIN.
- UI:NUser interaction, none
- Exploitation is triggered solely by the attacker transmitting malicious batman-adv mesh packets; no victim user action (mounting, DHCP client activity, or runtime configuration changes) is needed beyond the victim already running an active mesh node.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap memory within the batman-adv DAT subsystem on the mesh node and does not cross VM, container, or IOMMU boundaries to impact a separate security authority.
- C:HConfidentiality impact, high
- Stale hw_src dereferences freed skb buffer memory; batadv_dat_entry_add() reads six bytes via ether_addr_copy(dat_entry->mac_addr, hw_src), constituting a kernel heap use-after-free that can disclose sensitive or attacker-influenced memory contents.
- I:HIntegrity impact, high
- UAF-derived bytes are written into kmalloc'd batadv_dat_entry objects in the distributed ARP table hash, providing heap corruption suitable for developing arbitrary kernel memory write or control-flow hijacking primitives.
- A:HAvailability impact, high
- Use-after-free on the batman-adv RX path can cause kernel oops, panic, or hang when processing freed skb data during DAT updates, and associated heap corruption inherently threatens system availability even before full exploit development.