Look up another CVE · open CVE-2026-72226 in the interactive tracker
CVE-2026-72226
batman-adv: tt: prevent TVLV OOB check overflow
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-2026-72226 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
A TT unicast TVLV contains the number of VLANs stored in it. This number is an u16 and gets multiplied by the size of the struct batadv_tvlv_tt_vlan_data (8 bytes). The size can therefore overflow the u16 used to store the tt_vlan_len. All additional safety checks to prevent out-of-bounds access of the TVLV buffer are invalid due to this overflow. Using size_t prevents this overflow and ensures that the safety checks compare against the actual buffer requirements.
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/translation-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 -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
- 0.76%, higher than 54.2% 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 | 0de12a4c4847 |
| 3.13 | 5.15.212 | d6ff4764ff78 |
| 3.13 | 6.1.178 | 1898273c5dc8 |
| 3.13 | 6.6.145 | 604bd5042fbc |
| 3.13 | 6.12.97 | 7319c0794f91 |
| 3.13 | 6.18.40 | 3256c05d5a9d |
| 3.13 | 7.1.5 | 6222b4436865 |
| 3.13 | 7.2 | 7a581d9aaba8 |
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
- Crafted BATADV_UNICAST_TVLV frames from remote mesh peers reach batadv_tt_tvlv_unicast_handler_v1() via batadv_batman_skb_recv() → batadv_recv_unicast_tvlv() → batadv_tvlv_containers_process() without local syscall or ioctl access on the victim.
- AC:LAttack complexity, low
- An attacker reliably bypasses TVLV bounds checks by setting num_vlan so flex_array_size() overflows the u16 tt_vlan_len (e.g. 8192 VLANs wraps length to 4); all packet fields are attacker-controlled with no races or victim-state dependencies.
- PR:NPrivileges required, none
- batman-adv TVLV receive processing performs no authentication or capability check on senders; any unauthenticated mesh peer injecting ETH_P_BATMAN unicast TVLV frames to an active mesh node triggers the vulnerable path without Linux credentials on the victim.
- UI:NUser interaction, none
- Exploitation is triggered solely by the attacker transmitting malicious mesh packets; no victim mount, click, or runtime configuration change is required beyond batman-adv already being active on a mesh interface.
- S:UScope, unchanged
- Out-of-bounds reads and translation-table corruption occur within the victim kernel networking subsystem on the mesh node; the flaw does not cross VM, container, IOMMU, or other separate security-authority boundaries.
- C:HConfidentiality impact, high
- Overflowed tt_vlan_len invalidates the length check, so batadv_handle_tt_response() offsets tt_change by struct_size() far beyond the skb and _batadv_tt_update_changes() performs out-of-bounds reads of kernel memory for each computed entry.
- I:HIntegrity impact, high
- Out-of-bounds tt_change data drives batadv_tt_global_add()/batadv_tt_global_del() and batadv_tt_fill_gtable(), writing attacker-influenced or leaked bytes into kmalloc-backed translation-table objects suitable for heap corruption and control-flow hijacking.
- A:HAvailability impact, high
- Dereferencing tt_change pointers tens of kilobytes past the packet buffer can cause kernel oops or panic, and corrupt translation-table updates can destabilize or disable mesh routing on the victim node.