How severe is CVE-2026-86133?

CVE-2026-86133 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-86133 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-86133?

CVE-2026-86133 affects Watchguard Fireware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-86133?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-86133 published?

CVE-2026-86133 was published on 2026-09-30 and last updated on 2026-10-06.

CVE-2026-86133

CVE-2026-86133 is a high-severity vulnerability in Watchguard Fireware with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-191.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.2
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-191
Affected product: Watchguard Fireware
Published: 2026-09-30
Last modified: 2026-10-06

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.

Frequently asked questions

What is CVE-2026-86133?: 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.
How severe is CVE-2026-86133?: CVE-2026-86133 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-86133 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-86133?: CVE-2026-86133 affects Watchguard Fireware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-86133?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-86133 published?: CVE-2026-86133 was published on 2026-09-30 and last updated on 2026-10-06.

References

https://psirt.watchguard.com/CVE-2026-86133

Affected products (1)

cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:*

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