CVE-2026-86128 — Fireware
HIGHCVE-2026-86128 is a high-severity (CVSS 7.5) NULL Pointer Dereference vulnerability in watchguard fireware. A fix is available — see the affected versions and patch details below.
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…
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-86128.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-86128 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 382,795 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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.
Affected Products
firewarewatchguardDetection & mitigation playbook
Vendor / applianceDetect
Inventory every watchguard fireware deployment and check each version against the affected-products list above.
Fix
Apply the watchguard fireware security patch or hotfix for CVE-2026-86128 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2026-86128 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.