High severity · published Sep 29, 2026
CVE-2026-86128
Fireware OS NULL Pointer Dereference in NetFlow IPv6 Traffic Processing Allows Remote Denial of Service
7.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 30% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FO
Fireware OS · WatchGuard
2026.3 before 2026.3.2; 2025.0 before 2026.2.3; 12.0 before 12.12.3; 12.0 before 12.5.21 · source: vendor
FI
Fireware · Watchguard
12.0 before 12.5.21; 12.12 before 12.12.3; 2025.0 before 2026.2.3; 2026.3 before 2026.3.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-86128
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-86128
vendor-advisory
https://psirt.watchguard.com/CVE-2026-86128
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