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CVE-2026-72231
batman-adv: tt: avoid request storms during pending request
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-2026-72231 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
batadv_send_tt_request() allocates a tt_req_node when none exists for the destination originator node. This should prevent that a multiple TT requests are send at the same time to an originator. But if allocation of the send buffer failed, this request must be cleaned up again. But indicator for such a failure is "ret == false". But the actual implementation is checking for "ret == true". The check must be inverted to not loose the information about the TT request directly after it was attempted to be sent out. This should avoid potential request storms.
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
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.68%, higher than 51.3% 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 |
|---|---|---|
| 3.13 | 5.10.261 | 6055695ea40c |
| 3.13 | 5.15.212 | 21c44a6895f4 |
| 3.13 | 6.1.178 | 5e46c76d9a50 |
| 3.13 | 6.6.145 | 067e413eec2e |
| 3.13 | 6.12.97 | 716f434eb358 |
| 3.13 | 6.18.40 | 6a65ac8a81e9 |
| 3.13 | 7.1.5 | aba1cf21954e |
| 3.13 | 7.2 | 27c7d4000823 |
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
- The bug is reached when remote batman-adv OGM/TVLV packets are received on an active mesh hardif via batadv_batman_skb_recv() → batadv_iv_ogm_recv() → batadv_tvlv_ogm_receive() → batadv_tt_update_orig() → batadv_send_tt_request(), with no local syscall required on the victim.
- AC:LAttack complexity, low
- A mesh attacker can deterministically craft OGMs with mismatched TTVN/CRC to force the request_table path on every received OGM; the inverted ret check removes the pending tt_req_node after each successful send, eliminating deduplication so storms are repeatable without races.
- PR:NPrivileges required, none
- batman-adv OGM/TVLV processing performs no authentication or capability check on senders; any mesh peer that can inject ETH_P_BATMAN frames onto the victim's active hardif triggers the vulnerable path without Linux credentials on the victim host.
- UI:NUser interaction, none
- No victim user action is required once batman-adv is active; the kernel automatically processes incoming OGMs and issues TT_REQUEST unicasts in response to detected translation-table inconsistency, entirely driven by attacker-supplied mesh traffic.
- S:UScope, unchanged
- Impact is confined to excessive batman-adv translation-table control traffic and resource exhaustion on the victim mesh node within the kernel networking stack; it does not cross VM, container, IOMMU, or other security authority boundaries.
- C:NConfidentiality impact, none
- The inverted conditional is a pure logic error in tt_req_node list housekeeping; it causes neither out-of-bounds access, use-after-free, nor uninitialized data transmission, so no information-disclosure or memory-read primitive exists.
- I:NIntegrity impact, none
- No attacker-controlled kernel memory writes or data corruption occur; the bug only suppresses pending-request tracking so duplicate TT_REQUEST packets are emitted, flooding mesh bandwidth without modifying stored translation-table contents.
- A:HAvailability impact, high
- Removing the tt_req_node immediately after each successful TT_REQUEST disables the one-request-per-originator guard, letting a remote attacker drive unbounded GFP_ATOMIC allocations and mesh-wide TT_REQUEST storms that can exhaust CPU, memory, and link capacity on community mesh nodes.