Cyber Resilience

CVE-2026-86128

Memory Safety in Watchguard Fireware 12.0 – 12.5.21

Memory Safety
Published
30 September 2026
Modified
06 October 2026
Patch / advisory
View advisory
CVSS Score v4 8.2
Click a component to see what it means
Raw vectorCVSS: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
EPSS Score 0.0036 27th percentile
Risk Priority 43 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-86128 is a high-severity NULL Pointer Dereference (CWE-476) vulnerability in Watchguard Fireware. Its CVSS base score is 8.2 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Service Stop (T1489); ranked at the 27th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A10:2025 Mishandling of Exceptional Conditions

EU & UK References

Vulnerability Data

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.

CWE(s)
CWE-476

Related Threats

MITRE ATT&CK Enterprise Techniques

T1489 Service Stop Impact
Adversaries may stop or disable services on a system to render those services unavailable to legitimate users.
attack.mitre.org →
T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-60495Shared CWE-476
CVE-2023-53335Shared CWE-476
CVE-2023-1667Shared CWE-476
CVE-2026-60109Shared CWE-476
CVE-2026-86134Shared CWE-476
CVE-2024-57881Shared CWE-476
CVE-2025-38021Shared CWE-476
CVE-2026-10656Shared CWE-476
CVE-2026-13065Shared CWE-476
CVE-2025-48728Shared CWE-476

Affected Assets

watchguard
fireware
12.0 — 12.5.21 · 12.12 — 12.12.3 · 2025.0 — 2026.2.3

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation partial match

Developer testing and evaluation (including static analysis) directly finds null-dereference bugs before deployment.

SA-15 Development Process, Standards, and Tools partial match

Documented development standards and tools can enforce null-safety rules and safe pointer usage.

SA-8 Security and Privacy Engineering Principles partial match

Engineering principles can mandate defensive coding such as explicit null checks before dereference.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 partial match
prevents

Secure SDLC practices (static analysis, code review, safe coding standards) directly prevent NULL dereference bugs during development.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

References