CVE-2026-3987Network attack vector

Authenticated code execution via Web UI path traversal

Published Apr 1, 2026 · Updated Apr 1, 2026

Path traversal in WatchGuard Fireware OS Web UI allows remote authenticated users to execute code through an arbitrary file write. WatchGuard identifies the mechanism as an arbitrary file write via Web UI path traversal but does not disclose the affected endpoint or pathname operation. Device Administrator privileges and network access to the management interface are required; successful exploitation runs code in an elevated system process.

CVSS severity8.6
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in WatchGuard Fireware OS Web UI allows remote authenticated users to execute code through an arbitrary file write. WatchGuard identifies the mechanism as an arbitrary file write via Web UI path traversal but does not disclose the affected endpoint or pathname operation. Device Administrator privileges and network access to the management interface are required; successful exploitation runs code in an elevated system process.

The record

CVE
CVE-2026-3987
Published
Apr 1, 2026
Updated
Apr 1, 2026
Vendor
WatchGuard Technologies
Product
Fireware OS
Classifications
CWE-22, T1210
Attack vector
network
Privileges
admin

Timeline

How it unfolded

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

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=12.6.1 <=12.11.8
  2. Affected versionversion=2025.1 <=2026.1.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

WatchGuard Technologies · Fireware OSversion=12.6.1 <=12.11.8; version=2025.1 <=2026.1.2

Published CVSS scores

7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
8.6WatchGuard Technologies, Inc.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

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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1210Exploitation of Remote Services

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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