# CVE-2026-43100: linux: In the Linux kernel, the following vulnerability has been resolved: bridge: guard local VLAN-0 FDB helpers against N... CVE-2026-43100 is fixed in 19 products on 1 platform, first by ALAS2023-2026-1693, released May 8, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-43100 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0012 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 6, 2026 ## 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(). ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel-livepatch-6.18.25-55.108 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | linux Debian 14 | 6.19.14-1 | [DEBIAN-CVE-2026-43100](https://patchblox.com/security/data/fix/linux/debian-cve-2026-43100.md) | May 15, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.25-55.108.amzn2023 | [ALAS2023-2026-1693](https://patchblox.com/security/data/fix/linux/alas2023-2026-1693.md) | May 8, 2026 | --- Data as of 2026-11-08T19:12:23Z UTC. 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