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HIGH severity

CVE-2026-86133 — Fireware

HIGH

CVE-2026-86133 is a high-severity (CVSS 7.5) CWE-191 vulnerability in watchguard fireware. A fix is available — see the affected versions and patch details below.

An integer underflow vulnerability in the WatchGuard Fireware OS IKE daemon (iked) allows a remote attacker who has completed the initial IKEv2 handshake to crash the iked process by…

Published
Updated
Affected
1 product
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-86133.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs25th percentile — riskier than 25% of all scored CVEsHighest risk
0.00%0.28%0.56%0.84%0.3%0.3%Oct 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-86133 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 383,485 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Description

An integer underflow vulnerability in the WatchGuard Fireware OS IKE daemon (iked) allows a remote attacker who has completed the initial IKEv2 handshake to crash the iked process by sending a specially crafted encrypted IKEv2 message, resulting in a denial of service.

Affected Products

1 product · 4 configurations
OS
firewarewatchguard
≥ 2026.3 && < 2026.3.2
range

Detection & mitigation playbook

Vendor / appliance

  1. Detect

    Inventory every watchguard fireware deployment and check each version against the affected-products list above.

  2. Fix

    Apply the watchguard fireware security patch or hotfix for CVE-2026-86133 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

An integer underflow vulnerability in the WatchGuard Fireware OS IKE daemon (iked) allows a remote attacker who has completed the initial IKEv2 handshake to crash the iked process by sending a specially crafted encrypted IKEv2 message, resulting in a denial of service.
O3 Security · Runtime Protection

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