CVE-2026-86133: An integer underflow vulnerability in the WatchGuard Fireware OS IKE daemon (iked) allows a remote attacker wh

Q: How do I fix CVE-2026-86133?

fireware: upgrade to 12.5.21, 12.12.3, 2026.2.3, 2026.3.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-86133 being exploited?

CVE-2026-86133 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-86133 affect?

CVE-2026-86133 affects fireware. Severity is high (CVSS 7.5). 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, resu

Q: How urgent is CVE-2026-86133?

Priority 38/100. High severity; Remotely exploitable, no login, no user action

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-86133 is a high-severity flaw (CVSS 7.5) affecting fireware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 72%)
CISA exploited list	No
Weakness	CWE-191, CWE-1284
Published	2026-09-30
Last modified	2026-10-06

Publisher (CNA): WatchGuard Technologies, Inc. · Vendor: watchguard

Last updated 2026-10-06 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-30 00:16 UTCPublished CVE record published
2026-10-06 20:28 UTCUpdated Record last modified

watchguard fireware UPGRADE

Affected: >= 12.0 and < 12.5.21 · >= 12.12 and < 12.12.3 · >= 2025.0 and < 2026.2.3 · >= 2026.3 and < 2026.3.2

Fixed in: 12.5.21, 12.12.3, 2026.2.3, 2026.3.2

Safe to downgrade to: a release before 12.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-86133?

fireware: upgrade to 12.5.21, 12.12.3, 2026.2.3, 2026.3.2. Exact commands for each OS are on this page.

Is CVE-2026-86133 being exploited?

CVE-2026-86133 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-86133 affect?

CVE-2026-86133 affects fireware. Severity is high (CVSS 7.5). 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, resu

How urgent is CVE-2026-86133?

Priority 38/100. High severity; Remotely exploitable, no login, no user action

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References

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