# CVE-2026-104381: WatchGuard Fireware OS missing authentication in FireCluster state sync

Source: https://junglewise.ai/threats/cve-2026-104381-a-missing-authentication-vulnerability-in-fireware-os-s  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-104381 · Severity: info · Published 2026-10-27

WatchGuard Fireware OS is network security software that protects corporate networks using VPN tunnels. A missing authentication vulnerability in its FireCluster state synchronization feature allows an unauthenticated attacker on the cluster network to terminate VPN tunnels, disrupting secure remote access for employees and potentially causing business downtime.

Technologies: [Watchguard Fireware OS](https://junglewise.ai/threats/technologies/fireware-os). Vendors: [Watchguard](https://junglewise.ai/threats/vendors/watchguard).

## Quick answers

**Is CVE-2026-104381 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-104381 being exploited in the wild.

**How severe is CVE-2026-104381?** Informational severity, published 27 October 2026.

**Which products and versions are affected?** Watchguard Fireware OS 12.0 before 12.5.22; 12.0 before 12.12.4; 2025.1 before 2026.4.

**Is there a fix for CVE-2026-104381?** Yes: fixed in Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-104381 attacked?** It is attacked from the adjacent network, in a network appliance.

**Am I affected by CVE-2026-104381?** Check whether you run Watchguard Fireware OS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22

## Technical details

A missing authentication vulnerability (CWE-306, CWE-294) in Fireware OS's FireCluster state synchronization feature allows an unauthenticated attacker positioned on the cluster synchronization network segment to send crafted synchronization traffic that terminates BOVPN tunnels prematurely. The vulnerability requires the attacker to be on the cluster network and the appliance to be deployed as a FireCluster with at least one BOVPN tunnel configured; no patch has been released as of the advisory date.

## Affected products

- WatchGuard Fireware OS 12.0 before 12.5.22; 12.0 before 12.12.4; 2025.1 before 2026.4

## Timeline

- 2026-10-27: disclosed

## References

- [https://psirt.watchguard.com/CVE-2026-104381](https://psirt.watchguard.com/CVE-2026-104381)

## Related threats

- [WatchGuard Fireware OS integer overflow in WebSocket Access Portal](https://junglewise.ai/threats/cve-2026-93866-an-integer-overflow-vulnerability-in-the-websocket-connection)
- [WatchGuard Fireware OS authentication bypass in FireCluster daemon](https://junglewise.ai/threats/cve-2026-93865-a-missing-authentication-vulnerability-in-the-fireware-os)
- [WatchGuard Fireware OS arbitrary file overwrite via link following](https://junglewise.ai/threats/cve-2026-93864-a-link-following-vulnerability-in-watchguard-fireware-os-s)
- [WatchGuard Fireware OS out-of-bounds read in FireCluster Sync](https://junglewise.ai/threats/cve-2026-93862-an-out-of-bounds-read-vulnerability-in-the-firecluster-sync)
- [WatchGuard Fireware OS stack buffer overflow in SIP proxy](https://junglewise.ai/threats/cve-2026-93857-a-stack-based-buffer-overflow-vulnerability-in-fireware-os-s-sip)