CVE-2026-43100

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2026-05-06. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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().

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

May 6, 2026

Last Modified

May 11, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
No patch confirmed yet.
generic

bridge: guard local VLAN-0 FDB helpers against NULL vlan group - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/fb612d436ff0317659e45a91c25fd7d9516f5b1b
generic

bridge: guard local VLAN-0 FDB helpers against NULL vlan group - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/ddf0ec2d600e7dad62b89692749534d7900a732a
generic

bridge: guard local VLAN-0 FDB helpers against NULL vlan group - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1979645e1842cb7017525a61a0e0e0beb924d02a

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
linuxKernel @ 6.18.24—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 6.19~rc8-1~exp1 (129 versions)6.19.14-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 28× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 170 total refreshes for this CVE.

  1. 2026-09-13 16:47 UTCEPSS rescore
  2. 2026-09-12 15:01 UTCEPSS rescore
  3. 2026-09-11 16:53 UTCOSV refresh
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  18. 2026-08-23 20:25 UTCEG score recompute
  19. 2026-08-23 20:25 UTCGHSA enrichment
  20. 2026-08-23 00:19 UTCEPSS rescore
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  1. 2026-08-17 12:59 UTCEG score recompute
  2. 2026-08-17 12:59 UTCGHSA enrichment
  3. 2026-08-16 14:56 UTCEPSS rescore
  4. 2026-08-16 04:56 UTCEG score recompute
  5. 2026-08-16 04:56 UTCGHSA enrichment
  6. 2026-08-16 02:14 UTCEPSS rescore
  7. 2026-08-15 01:30 UTCEPSS rescore
  8. 2026-08-14 03:31 UTCEG score recompute
  9. 2026-08-14 03:31 UTCGHSA enrichment
  10. 2026-08-13 22:00 UTCEPSS rescore
  11. 2026-08-13 01:51 UTCEG score recompute
  12. 2026-08-13 01:51 UTCGHSA enrichment
  13. 2026-08-12 13:51 UTCEPSS rescore
  14. 2026-08-12 02:02 UTCEG score recompute
  15. 2026-08-12 02:02 UTCGHSA enrichment
  16. 2026-08-11 13:43 UTCEPSS rescore
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  18. 2026-08-11 02:14 UTCGHSA enrichment
  19. 2026-08-11 00:00 UTCEPSS rescore
  20. 2026-08-10 02:25 UTCEG score recompute
  21. 2026-08-10 02:25 UTCGHSA enrichment
  22. 2026-08-09 13:46 UTCEPSS rescore
  23. 2026-08-09 02:37 UTCEG score recompute
  24. 2026-08-09 02:37 UTCGHSA enrichment
  25. 2026-08-08 16:37 UTCEPSS rescore
  26. 2026-08-08 01:44 UTCEG score recompute
  27. 2026-08-08 01:44 UTCGHSA enrichment
  28. 2026-08-07 01:55 UTCEG score recompute
  29. 2026-08-07 01:55 UTCGHSA enrichment
  30. 2026-08-06 13:46 UTCEPSS rescore
  31. 2026-08-05 22:23 UTCEG score recompute
  32. 2026-08-05 22:23 UTCGHSA enrichment
  33. 2026-08-04 15:10 UTCEPSS rescore
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  35. 2026-08-03 19:54 UTCEG score recompute
  36. 2026-08-03 19:54 UTCGHSA enrichment
  37. 2026-08-03 10:36 UTCEPSS rescore
  38. 2026-08-02 05:11 UTCEG score recompute
  39. 2026-08-02 05:11 UTCGHSA enrichment
  40. 2026-08-02 02:27 UTCEPSS rescore
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  42. 2026-07-30 16:28 UTCEPSS rescore
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  51. 2026-07-23 03:13 UTCEG score recompute
  52. 2026-07-22 14:08 UTCEPSS rescore
  53. 2026-07-21 15:24 UTCEPSS rescore
  54. 2026-07-20 17:08 UTCEPSS rescore
  55. 2026-07-19 17:48 UTCOSV refresh
  56. 2026-07-19 14:31 UTCEPSS rescore
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  66. 2026-07-09 19:10 UTCEPSS rescore
  67. 2026-07-08 15:16 UTCEPSS rescore
  68. 2026-07-07 13:46 UTCEPSS rescore
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  74. 2026-06-30 23:22 UTCEPSS rescore
  75. 2026-06-29 14:06 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-43100?
CVE-2026-43100 is a medium vulnerability published on May 6, 2026. In the Linux kernel, the following vulnerability has been resolved: bridge: guard local VLAN-0 FDB helpers against NULL vlan group When CONFIGBRIDGEVLANFILTERING is not set, brvlan_group() and nbpvlangroup() return NULL (br_private.h stub definitions). The BRBOOLOPTFDBLOCALVLAN_0 toggle code is…
When was CVE-2026-43100 disclosed?
CVE-2026-43100 was first published in the National Vulnerability Database on May 6, 2026, with the most recent update on May 11, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-43100 actively exploited?
CVE-2026-43100 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 97.8% of all scored CVEs.
What is the CVSS score of CVE-2026-43100?
CVE-2026-43100 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-43100?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-43100, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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