# CVE-2026-93862: WatchGuard Fireware OS out-of-bounds read in FireCluster Sync

Source: https://junglewise.ai/threats/cve-2026-93862-an-out-of-bounds-read-vulnerability-in-the-firecluster-sync  
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-2026-93862 · Severity: info · Published 2026-10-27

WatchGuard Fireware OS, which powers business firewalls deployed in clustered configurations, contains an out-of-bounds read vulnerability in its cluster synchronization feature. An attacker with access to the cluster network can crash the synchronization process repeatedly, causing a sustained denial of service and preventing the firewall cluster from functioning properly.

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

## Quick answers

**Is CVE-2026-93862 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93862 being exploited in the wild.

**How severe is CVE-2026-93862?** Informational severity, published 27 October 2026.

**Which products and versions are affected?** Watchguard Fireware OS 2025.1 to 2026.3, 12.0 to 12.12.3 (Default and T15/T35 with different ranges).

**Is there a fix for CVE-2026-93862?** Yes: fixed in Fireware OS 2026.4, 12.12.4, 12.5.22. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-93862 attacked?** It is attacked over the network or from the adjacent network.

**Am I affected by CVE-2026-93862?** 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, 12.12.4, 12.5.22

## Technical details

An out-of-bounds read in FireCluster Sync processing (CWE-125, CWE-129, CWE-787, CWE-823) allows an attacker on the cluster interconnect—such as a compromised cluster peer or on-path network attacker—to send specially crafted network traffic that triggers the vulnerability. Exploitation results in repeated crashes of the cluster synchronization process, achieving sustained denial of service. A fix is available in Fireware OS 2026.4, 12.12.4, and 12.5.22.

## Affected products

- WatchGuard Fireware OS 2025.1 to 2026.3, 12.0 to 12.12.3 (Default and T15/T35 with different ranges)

## Timeline

- 2026-10-27: disclosed
- 2026-10-27: advisory

## References

- [https://psirt.watchguard.com/CVE-2026-93862](https://psirt.watchguard.com/CVE-2026-93862)

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- [WatchGuard Fireware OS XPath injection in SSH authentication](https://junglewise.ai/threats/cve-2026-93434-an-xpath-injection-vulnerability-in-watchguard-fireware-os-s-ssh)