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CVE-2026-43100— bridge: guard local VLAN-0 FDB helpers against NULL vlan group

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于当CONFIG_BRIDGE_VLAN_FILTERING未设置时，br_vlan_group返回NULL导致空指针解引用。

AI Predicted 7.8 Difficulty: Easy EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 21446c06b441b9c993870efae71aef4e9aa72ec7< fb612d436ff0317659e45a91c25fd7d9516f5b1b affected
21446c06b441b9c993870efae71aef4e9aa72ec7< ddf0ec2d600e7dad62b89692749534d7900a732a affected
21446c06b441b9c993870efae71aef4e9aa72ec7< 1979645e1842cb7017525a61a0e0e0beb924d02a affected
6.18 affected
< 6.18 unaffected
6.18.24≤ 6.18.* unaffected
6.19.14≤ 6.19.* unaffected
7.0≤ * unaffected
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I. Basic Information for CVE-2026-43100

Vulnerability Information
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Vulnerability Title
bridge: guard local VLAN-0 FDB helpers against NULL vlan group
Source: CVE Program / CVE List V5
Vulnerability Description
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().
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于当CONFIG_BRIDGE_VLAN_FILTERING未设置时，br_vlan_group返回NULL导致空指针解引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 21446c06b441b9c993870efae71aef4e9aa72ec7 ~ fb612d436ff0317659e45a91c25fd7d9516f5b1b -
Linux Linux 6.18 -

II. Public POCs for CVE-2026-43100

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III. Intelligence Information for CVE-2026-43100

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Patches & Fixes for CVE-2026-43100 (3)

Same Patch Batch · Linux · 2026-05-06 · 224 CVEs total

CVE-2026-43208 9.8 CRITICAL net: do not pass flow_id to set_rps_cpu()
CVE-2026-43125 9.8 CRITICAL dlm: validate length in dlm_search_rsb_tree
CVE-2026-43198 9.8 CRITICAL tcp: fix potential race in tcp_v6_syn_recv_sock()
CVE-2026-43186 9.8 CRITICAL ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()
CVE-2026-43185 9.8 CRITICAL ksmbd: fix signededness bug in smb_direct_prepare_negotiation()
CVE-2026-43114 9.4 CRITICAL netfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry
CVE-2026-43117 9.1 CRITICAL btrfs: tracepoints: get correct superblock from dentry in event btrfs_sync_file()
CVE-2026-43197 9.1 CRITICAL netconsole: avoid OOB reads, msg is not nul-terminated
CVE-2026-43083 9.1 CRITICAL net: ioam6: fix OOB and missing lock
CVE-2026-43158 8.8 HIGH xfs: fix freemap adjustments when adding xattrs to leaf blocks
CVE-2026-43112 8.8 HIGH fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath
CVE-2026-43113 8.8 HIGH wifi: wl1251: validate packet IDs before indexing tx_frames
CVE-2026-43110 8.8 HIGH wifi: brcmfmac: validate bsscfg indices in IF events
CVE-2026-43249 8.8 HIGH 9p/xen: protect xen_9pfs_front_free against concurrent calls
CVE-2026-43239 8.8 HIGH smb: client: prevent races in ->query_interfaces()
CVE-2026-43232 8.8 HIGH net: wan: farsync: Fix use-after-free bugs caused by unfinished tasklets
CVE-2026-43283 8.8 HIGH net: ethernet: ec_bhf: Fix dma_free_coherent() dma handle
CVE-2026-43172 8.8 HIGH wifi: iwlwifi: fix 22000 series SMEM parsing
CVE-2026-43176 8.8 HIGH wifi: rtw89: pci: validate release report content before using for RTL8922DE
CVE-2026-43187 8.8 HIGH xfs: delete attr leaf freemap entries when empty

Showing top 20 of 224 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43100

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