CVE-2026-86128 Fireware OS NULL Pointer Dereference in NetFlow IPv6 Traffic Processing Allows Remote Denial of Service

What is CVE-2026-86128?

CVE-2026-86128 is a high-severity vulnerability in Watchguard Fireware, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-476

Which versions are affected by CVE-2026-86128?

It affects 1 product.

Products include Watchguard Fireware.

How do I fix CVE-2026-86128?

No fix has been published for CVE-2026-86128 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-86128 being exploited?

There is no known exploitation of CVE-2026-86128 in the wild and no public exploit code.

Other vulnerabilities in Watchguard Fireware

• CVE-2022-26318 WatchGuard Firebox and XTM Appliances Arbitrary Code Execution Exploited Critical 9.8
• CVE-2025-14733 WatchGuard Firebox Out of Bounds Write Exploited Critical 9.3
• CVE-2025-9242 WatchGuard Firebox Out-of-Bounds Write Exploited Critical 9.3
• CVE-2022-23176 WatchGuard Firebox and XTM Privilege Escalation Exploited High 8.8
• CVE-2022-31789 Integer overflow in n/a Critical 9.8

All Watchguard Fireware vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-pch3-5p8f-436q.