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CVE-2026-72234
batman-adv: access unicast_ttvn skb->data only after skb realloc
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-2026-72234 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. This was done correctly for the ethernet header but missed for the unicast_packet pointer.
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/routing.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
- 2026-08-15 (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 |
|---|---|---|
| 3.13 | 5.10.261 | aa9558af8599 |
| 3.13 | 5.15.212 | 9c2c05629e46 |
| 3.13 | 6.1.178 | 7b162b36de75 |
| 3.13 | 6.6.145 | ed90eb5c6842 |
| 3.13 | 6.12.97 | 979175834a69 |
| 3.13 | 6.18.40 | b8afcf799b2c |
| 3.13 | 7.1.5 | 9a7b72487981 |
| 3.13 | 7.2 | 7141990add3f |
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 in batadv_check_unicast_ttvn() when batadv_batman_skb_recv() processes incoming BATADV unicast packets from remote mesh peers on hard interfaces; crafted batman-adv frames reach the vulnerable code over the mesh network without local system access.
- AC:LAttack complexity, low
- An attacker reliably triggers the UAF by sending a batman-adv unicast packet with a VLAN-tagged embedded Ethernet header to a victim node; packet fields are attacker-controlled and can force batadv_get_vid()'s pskb_may_pull() to reallocate the skb buffer.
- PR:NPrivileges required, none
- No privileges are required on the victim host; exploitation only needs batman-adv active on an interface while the attacker acts as an unauthenticated mesh peer able to transmit batman-adv protocol frames to the target node.
- UI:NUser interaction, none
- No victim user interaction is needed; the kernel automatically processes the malicious batman-adv unicast packet on receive through the normal mesh routing receive path.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap memory within the same host networking subsystem and does not cross VM, container, or IOMMU boundaries to impact a separate security authority.
- C:HConfidentiality impact, high
- The stale unicast_packet pointer dereferences freed skb buffer memory for reads (unicast_packet->dest, unicast_packet->ttvn), constituting a kernel heap use-after-free that can disclose sensitive memory contents.
- I:HIntegrity impact, high
- The stale pointer is used for writes via ether_addr_copy(unicast_packet->dest) and unicast_packet->ttvn updates in reroute paths, enabling heap corruption and potential arbitrary kernel code execution.
- A:HAvailability impact, high
- Use-after-free on the skb data buffer during batman-adv unicast processing can cause kernel oops, panic, or hang, and UAF heap corruption inherently threatens system availability even before full exploit development.