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CVE-2026-52922
batman-adv: dat: handle forward allocation error
Published 2026-06-24 (4 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-2026-52922 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 | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
batadv_dat_forward_data() calls pskb_copy_for_clone() to duplicate an skb for each DHT candidate, but does not check the return value before passing it to batadv_send_skb_prepare_unicast_4addr(). That function dereferences the skb unconditionally, so a failed allocation triggers a NULL pointer dereference. Skip forwarding to the current DHT candidate on allocation failure.
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
- 2026-06-24 (4 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
- 0.39%, higher than 31.4% 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 |
|---|---|---|
| 3.8 | 5.10.258 | 9bcebaedfb84 |
| 3.8 | 5.15.209 | 2edb8aeb3cdd |
| 3.8 | 6.1.175 | ce0c38119940 |
| 3.8 | 6.6.142 | 866ac1d57040 |
| 3.8 | 6.12.92 | 4d420d9ee70a |
| 3.8 | 6.18.34 | 9cceea8eeba7 |
| 3.8 | 7.0.11 | cf48e75fc4fe |
| 3.8 | 7.1 | 2d8826a2d365 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
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 vulnerable DAT forwarding path is reachable through attacker-supplied batman-adv mesh traffic carrying ARP/DHCP payloads, processed in the kernel receive/network path without a local syscall. Scoring the highest defensible deployment, a remote mesh participant can send packets to the affected node.
- AC:LAttack complexity, low
- The packet format checks are straightforward and DAT is enabled by default when built; the attacker can repeatedly send valid ARP/DHCP-triggering traffic toward DAT candidates. Although the NULL dereference requires `GFP_ATOMIC` allocation failure, traffic flooding can plausibly create or hit that condition, so the higher-severity AC:L is selected.
- PR:NPrivileges required, none
- The receive path has no authentication or authorization gate for a peer that can transmit batman-adv mesh packets to the node. Privileges are only needed to configure the victim mesh, not to trigger the bug as a remote sender.
- UI:NUser interaction, none
- No victim user action is required after the affected batman-adv mesh is active. The attacker triggers the path by sending network traffic.
- S:UScope, unchanged
- The impact is within the vulnerable kernel instance and does not cross a separate security authority such as a hypervisor or sandbox boundary. Standard kernel availability impact is scope unchanged.
- C:NConfidentiality impact, none
- The bug is a NULL `skb` dereference after `pskb_copy_for_clone()` failure, not a use-after-free or out-of-bounds access. The investigated path shows no attacker-controlled memory disclosure primitive.
- I:NIntegrity impact, none
- The NULL pointer is dereferenced immediately in skb header preparation and does not provide an attacker-controlled write or control-flow primitive. There is no evidence of memory corruption beyond the crash.
- A:HAvailability impact, high
- A failed allocation leads to an unchecked NULL pointer dereference in kernel networking code. This can oops or panic the kernel, causing high availability impact.