CVE-2026-86128

Fireware OS NULL Pointer Dereference in NetFlow IPv6 Traffic Processing Allows Remote Denial of Service

At a glance

Severity: HIGH 8.2
EPSS: EPSS 0.36 % · percentile 30 (2026-10-27)
State: PUBLISHED
Published: 2026-09-29
Updated: 2026-09-30
Assigner: WatchGuard
NVD status: Analyzed

Description

A NULL pointer dereference vulnerability in Fireware OS's NetFlow packet-processing feature allows a remote, unauthenticated attacker to cause a denial of service by sending a specially crafted IPv6 packet.

Scores

Version	Score	Vector	Scored by
CVSS 4.0	HIGH 8.2	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N	WatchGuard
CVSS 4.0	HIGH 8.2	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X	NVD · 5d1c2695-1a31-4499-88ae-e847036fd7e3 (Secondary)
CVSS 3.1	HIGH 7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	NVD · nvd@nist.gov (Primary)

Weaknesses (CWE)

CWE-476

European references

ENISA EUVD · EUVD-2026-89489
GCVE · GCVE-0-2026-86128

Affected configurations (NVD CPE)

cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:* ≥ 12.0 < 12.5.21
cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:* ≥ 12.12 < 12.12.3
cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:* ≥ 2025.0 < 2026.2.3
cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:* ≥ 2026.3 < 2026.3.2

Affected products

Product	Versions
WatchGuard · Fireware OS	affected 2026.3 < 2026.3.2 ; affected 2025.0 < 2026.2.3 ; affected 12.0 < 12.12.3
WatchGuard · Fireware OS	affected 12.0 < 12.5.21

References

https://psirt.watchguard.com/CVE-2026-86128

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD