High severity · published Sep 29, 2026
CVE-2026-86133
Fireware OS Pre-Authentication Integer Underflow in iked Allows Remote Denial of Service
7.5
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 28% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FO
Fireware OS · WatchGuard
2026.3 before 2026.3.2; 2025.0 before 2026.2.3; 12.0 before 12.12.3; 12.0 before 12.5.21 · source: vendor
FI
Fireware · Watchguard
12.0 before 12.5.21; 12.12 before 12.12.3; 2025.0 before 2026.2.3; 2026.3 before 2026.3.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-86133
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-86133
vendor-advisory
https://psirt.watchguard.com/CVE-2026-86133
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