# CVE-2026-104381: Fireware OS Missing Authentication in FireCluster State Sync Allows BOVPN Tunnel Denial of Service

Status: published. Published: 2026-10-27. Updated: 2026-11-04.

A missing authentication vulnerability in Fireware OS's FireCluster state synchronization feature allows an unauthenticated attacker positioned on the cluster synchronization network segment to force premature VPN tunnel termination by sending crafted cluster synchronization traffic.

## Remediation

- fix: Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22 (source: CNA: WatchGuard)

## Affected products and versions

- WatchGuard / Fireware OS: ≥ 2025.1; < 2026.4 (affected, custom); ≥ 12.0; < 12.12.4 (affected, custom). Source: CNA: WatchGuard; platforms: Default
- WatchGuard / Fireware OS: ≥ 12.0; < 12.5.22 (affected, custom). Source: CNA: WatchGuard; platforms: T15/T35

## Severity and prioritization

- CVSS 4.0: 6 (medium); CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N; source: CNA: WatchGuard

- CISA KEV: No listing in collected sources

- EPSS: 0.13% as of 2026-11-04; percentile 2.89%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-294, CWE-306, CWE-345

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://psirt.watchguard.com/CVE-2026-104381 (CNA: WatchGuard; vendor-advisory)

## Provenance

- CNA: WatchGuard: https://www.cve.org/CVERecord?id=CVE-2026-104381; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-104381; retrieved 2026-11-04; source updated Not reported

Revision: 950db5a6cbbf40041b6d56b353df8125a87cb062a5b31f431d1f45982ce4f253

Canonical: https://y2.dev/cve/CVE-2026-104381

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