CVE-2026-43100

Local system crash via VLAN-group NULL dereference

Published May 6, 2026 · Updated May 6, 2026

NULL pointer dereference in Linux Kernel bridge code allows local users to crash the system via a crafted RTM_NEWLINK request. The bridge VLAN-0 FDB insert and delete helpers iterate vg->vlan_list after br_vlan_group() or nbp_vlan_group() returns NULL. Reachability requires a kernel built without CONFIG_BRIDGE_VLAN_FILTERING and local privileges to create a bridge with BR_BOOLOPT_FDB_LOCAL_VLAN_0.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux Kernel bridge code allows local users to crash the system via a crafted RTM_NEWLINK request. The bridge VLAN-0 FDB insert and delete helpers iterate vg->vlan_list after br_vlan_group() or nbp_vlan_group() returns NULL. Reachability requires a kernel built without CONFIG_BRIDGE_VLAN_FILTERING and local privileges to create a bridge with BR_BOOLOPT_FDB_LOCAL_VLAN_0.

The record

CVE
CVE-2026-43100
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=21446c06b441b9c993870efae71aef4e9aa72ec7 <1979645e1842cb7017525a61a0e0e0beb924d02a
  2. Affected versionversion=21446c06b441b9c993870efae71aef4e9aa72ec7 <ddf0ec2d600e7dad62b89692749534d7900a732a
  3. Affected versionversion=21446c06b441b9c993870efae71aef4e9aa72ec7 <fb612d436ff0317659e45a91c25fd7d9516f5b1b
  4. Affected versionversion=6.18

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=21446c06b441b9c993870efae71aef4e9aa72ec7 <1979645e1842cb7017525a61a0e0e0beb924d02a; version=21446c06b441b9c993870efae71aef4e9aa72ec7 <ddf0ec2d600e7dad62b89692749534d7900a732a; version=21446c06b441b9c993870efae71aef4e9aa72ec7 <fb612d436ff0317659e45a91c25fd7d9516f5b1b; version=6.18

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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