High8.6WatchGuard

High [CVE-2026-3987] WatchGuard Firebox Arbitrary File Write vis Path Traversal in Fireware Web UI

This high-severity WatchGuard advisory covers CVE-2026-3987 affecting Fireware OS.

CVE-2026-3987 Published Apr 1, 2026Updated by vendor Aug 10, 2026

CVE-2026-3987

Affected products & platforms

WatchGuardFirebox / Fireware

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Summary

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.

Affected versions

Fireware OS 2025.1 before 2026.2
Fireware OS 12.6.1 before 12.12

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

Fixed versions

2026.2
12.12

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

Mitigation

Upgrade to a fixed release: 2026.2, 12.12. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 15 days ago·verify at source

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