# CVE-2026-86134: WatchGuard Fireware OS NULL pointer dereference in authentication

Source: https://junglewise.ai/threats/cve-2026-86134-a-null-pointer-dereference-vulnerability-in-the-watchguard  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-30. Updated: 2026-09-30  
License: CC BY 4.0 with a link back

CVE-2026-86134 · Severity: info · Published 2026-09-30

WatchGuard Fireware OS, which manages network firewalls and security gateways, contains a flaw in its authentication system that allows an attacker to remotely crash the management interface without logging in. This denial of service could temporarily disable administrative access to critical network security appliances.

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

## Quick answers

**Is CVE-2026-86134 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86134 being exploited in the wild.

**How severe is CVE-2026-86134?** Informational severity, published 30 September 2026.

**Which products and versions are affected?** Watchguard Fireware OS 12.0 through 12.12.2; 2025.0 through 2026.2.2; 2026.3 through 2026.3.1. T15/T35 models: 12.0 through 12.5.20.

**Is there a fix for CVE-2026-86134?** A patch was published on 2026-09-30: Fireware OS 12.12.3, 12.5.21, 2026.2.3, 2026.3.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86134 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-86134?** 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.

## Technical details

A NULL pointer dereference exists in the Fireware OS authentication daemon that processes login requests. A remote unauthenticated attacker can trigger this crash by sending a specially crafted request to the login interface, causing the management daemon to terminate and resulting in denial of service.

## Affected products

- WatchGuard Fireware OS 12.0 through 12.12.2; 2025.0 through 2026.2.2; 2026.3 through 2026.3.1. T15/T35 models: 12.0 through 12.5.20

## Timeline

- 2026-09-30: disclosed
- 2026-09-30: patched: Fireware OS 12.12.3, 12.5.21, 2026.2.3, 2026.3.2

## References

- [https://psirt.watchguard.com/CVE-2026-86134](https://psirt.watchguard.com/CVE-2026-86134)

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