🛡️ CVE-2026-43100 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

bridge: guard local VLAN-0 FDB helpers against NULL vlan group

In the Linux kernel, the following vulnerability has been resolved:

bridge: guard local VLAN-0 FDB helpers against NULL vlan group

When CONFIG_BRIDGE_VLAN_FILTERING is not set, br_vlan_group() and

nbp_vlan_group() return NULL (br_private.h stub definitions). The

BR_BOOLOPT_FDB_LOCAL_VLAN_0 toggle code is compiled unconditionally and

reaches br_fdb_delete_locals_per_vlan_port() and

br_fdb_insert_locals_per_vlan_port(), where the NULL vlan group pointer

is dereferenced via list_for_each_entry(v, &vg->vlan_list, vlist).

The observed crash is in the delete path, triggered when creating a

bridge with IFLA_BR_MULTI_BOOLOPT containing BR_BOOLOPT_FDB_LOCAL_VLAN_0

via RTM_NEWLINK. The insert helper has the same bug pattern.

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000056: 0000 [#1] KASAN NOPTI

KASAN: null-ptr-deref in range [0x00000000000002b0-0x00000000000002b7]

RIP: 0010:br_fdb_delete_locals_per_vlan+0x2b9/0x310

Call Trace:

br_fdb_toggle_local_vlan_0+0x452/0x4c0

br_toggle_fdb_local_vlan_0+0x31/0x80 net/bridge/br.c:276

br_boolopt_toggle net/bridge/br.c:313

br_boolopt_multi_toggle net/bridge/br.c:364

br_changelink net/bridge/br_netlink.c:1542

br_dev_newlink net/bridge/br_netlink.c:1575

Add NULL checks for the vlan group pointer in both helpers, returning

early when there are no VLANs to iterate. This matches the existing

pattern used by other bridge FDB functions such as br_fdb_add() and

br_fdb_delete().

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

CVE-2026-43100 is recorded against 2 packages.

  • kernel (from 6.19.0 up to 6.19.14)
  • linux-kernel

Timeline and source

Published on 6 May 2026 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2026-43100 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-05-06
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.19.0 6.19.14
linux-kernel — —

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