Cyber Resilience

CVE-2026-3987

High

Published: 01 April 2026

Published
01 April 2026
Modified
03 April 2026
KEV Added
—
Patch
—
CVSS Score v4 8.6 CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/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 0.0059 43.5th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-3987 is a high-severity Path Traversal (CWE-22) vulnerability in Watchguard (inferred from references). Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 43.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability details

A path traversal vulnerability in the Fireware OS Web UI on WatchGuard Firebox systems may allow a privileged authenticated remote attacker to execute arbitrary code in the context of an elevated system process.This issue affects Fireware OS 12.6.1 up to…

more

and including 12.11.8 and 2025.1 up to and including 2026.1.2.

CWE(s)
CWE-22

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Path traversal in public Web UI directly enables remote code execution via exploitation of a public-facing application (CWE-22).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2025-2505Shared CWE-22
CVE-2026-5841Shared CWE-22
CVE-2026-33242Shared CWE-22
CVE-2026-33292Shared CWE-22
CVE-2026-35605Shared CWE-22
CVE-2025-53632Shared CWE-22
CVE-2025-8110Shared CWE-22
CVE-2026-8757Shared CWE-22
CVE-2025-7712Shared CWE-22
CVE-2026-31817Shared CWE-22

Affected Assets

Watchguard
—
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-10 Information Input Validation
addresses: CWE-22

Validates pathnames and filenames to prevent traversal outside intended directories.

References