CVE-2026-86128Network attack vector

Unauthenticated service interruption via NetFlow IPv6 dereference

Published Sep 29, 2026 · Updated Sep 29, 2026

NULL pointer dereference in WatchGuard Technologies, Inc. Fireware OS allows remote attackers to interrupt service with crafted IPv6 packets. The NetFlow packet-processing path dereferences a null pointer while handling the packet; public details do not identify the function or malformed field. Exposure depends on NetFlow processing IPv6 traffic on a monitored interface, and the available advisory text does not establish whether the interruption is a crash, hang, or reboot.

CVSS severityUnavailable
Unscored
EPSS probability0.36%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in WatchGuard Technologies, Inc. Fireware OS allows remote attackers to interrupt service with crafted IPv6 packets. The NetFlow packet-processing path dereferences a null pointer while handling the packet; public details do not identify the function or malformed field. Exposure depends on NetFlow processing IPv6 traffic on a monitored interface, and the available advisory text does not establish whether the interruption is a crash, hang, or reboot.

The record

CVE
CVE-2026-86128
Published
Sep 29, 2026
Updated
Sep 29, 2026
Vendor
WatchGuard Technologies, Inc.
Product
Fireware OS
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=12.0 <12.12.3
  2. Affected versionversion=12.0 <12.5.21
  3. Affected versionversion=2025.0 <2026.2.3
  4. Affected versionversion=2026.3 <2026.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WatchGuard Technologies, Inc. · Fireware OSversion=12.0 <12.12.3; version=12.0 <12.5.21; version=2025.0 <2026.2.3; version=2026.3 <2026.3.2

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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