CVE-2026-3987
Authenticated path traversal in Fireware OS Web UI enables code execution with elevated privileges.
Is CVE-2026-3987 being exploited?
Not confirmed. CVE-2026-3987 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.68% probability of exploitation in the next 30 days.
How severe is CVE-2026-3987?
CVE-2026-3987 is rated High with a CVSS score of 8.6. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-3987?
Yes. A fix has been recorded for CVE-2026-3987. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-3987 affect?
CVE-2026-3987 affects WatchGuard Firebox devices (Fireware OS 12.6.1–12.11.8, 2025.1–2026.1.2). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-3987?
Upgrade Fireware OS to patched version per WatchGuard release notes.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated remote code execution on WatchGuard Firebox via path traversal; elevated system privileges.
Immediate action required
- affected>= 2025.1 and < 2026.2
- affected>= 12.6.1 and < 12.12
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.