# CVE-2026-86132: WatchGuard Fireware OS integer underflow in IKEv2 daemon

Source: https://junglewise.ai/threats/cve-2026-86132-an-integer-underflow-vulnerability-in-the-watchguard-fireware-os  
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-2026-86132 · Severity: info · Published 2026-09-30

WatchGuard Fireware OS is the operating system running on WatchGuard network firewalls, which protect enterprise networks and control traffic flow. An integer underflow vulnerability in the IKEv2 daemon allows a remote attacker without credentials to crash the firewall's VPN service by sending a specially crafted encrypted message, resulting in a denial of service and potential business disruption.

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

## Quick answers

**Is CVE-2026-86132 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86132 being exploited in the wild.

**How severe is CVE-2026-86132?** Informational severity, published 30 September 2026.

**Which products and versions are affected?** Watchguard Fireware OS 2026.3 < 2026.3.2, 2025.0 < 2026.2.3, 12.0 < 12.12.3; Watchguard Fireware OS T15/T35 12.0 < 12.5.21.

**Is there a fix for CVE-2026-86132?** A patch was published on 2026-09-29: Fireware OS 2026.3.2, 2026.2.3, 12.12.3, and 12.5.21 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86132 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-86132?** Check whether you run Watchguard Fireware OS or Watchguard Fireware OS T15/T35 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

An integer underflow (CWE-191) in the IKEv2 daemon (iked) occurs when processing encrypted IKEv2 messages negotiated with AES-GCM cipher suites. The vulnerability is pre-authentication and network-accessible, allowing an unauthenticated remote attacker to trigger a denial of service by crashing the iked process. No active exploitation in the wild has been reported.

## Affected products

- WatchGuard Fireware OS 2026.3 < 2026.3.2, 2025.0 < 2026.2.3, 12.0 < 12.12.3
- WatchGuard Fireware OS T15/T35 12.0 < 12.5.21

## Timeline

- 2026-09-29: disclosed
- 2026-09-29: patched: Fireware OS 2026.3.2, 2026.2.3, 12.12.3, and 12.5.21 released

## References

- [https://psirt.watchguard.com/CVE-2026-86132](https://psirt.watchguard.com/CVE-2026-86132)

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