WatchGuard Firebox iked Out of Bounds Write Vulnerability

Primary CVSS: v4.0 9.3 CRITICAL from 5d1c2695-1a31-4499-88ae-e847036fd7e3

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.913000000 probability, percentile 0.998020000 (date 2026-08-21)

CISA KEV: Listed on 2025-11-12; due 2025-12-03; ransomware use Unknown

Problem Types: CWE-787 | CWE-787 CWE-787

Discovery Credit

CNA: btaol (en)

Solutions

CNA: Fireware OS 2025.1.1, Fireware OS 12.11.4, Fireware OS 12.5.13, Fireware OS 12.3.1+722811

Workarounds

CNA: If your Firebox is only configured with Branch Office VPN tunnels to static gateway peers and you are not able to immediately upgrade the device to a version of Fireware OS with the vulnerability resolution, you can follow WatchGuard’s recommendations for Secure Access to Branch Office VPNs that Use IPSec and IKEv2 as a temporary workaround.

Exploits

CNA: We have evidence that suggests this vulnerability is under active exploitation. Indicators of Attack We are providing the following Indicators of Attack (IoAs) to help device owners identify potential attempts to exploit this vulnerability against vulnerable Firebox appliances. These IoAs are only applicable on devices that lack the resolution described later in this advisory. Abnormally large IKE_AUTH request IDi payload With iked diagnostic logging set to the Info logging level, the iked process generates a log message when the Firebox receives an IKE_AUTH request message. An IKE_AUTH request log message with an abnormally large IDi payload size (greater than 100 bytes) is a strong indicator of an attack. The following example diagnostic log shows an example IDi payload size of 300 bytes. 1970-01-01 01:00:00 iked (203.0.113.1<->203.0.113.2)"IKE_AUTH request" message has 6 payloads [ IDi(sz=300) CERT(sz=889) SA(sz=44) TSi(sz=24) TSr(sz=24) N(sz=8)] IKE Process Hang During a successful exploit, the IKED process (responsible for handling IKE negotiations) will hang, interrupting VPN tunnel negotiations and re-keys. This is a strong indicator of attack. Existing tunnels may continue to pass traffic. IKED Process Crash After a failed or successful exploit, the IKED process will crash and generate a fault report on the Firebox. Be aware, there are other situations that could cause the IKED process to crash. This is a weak indicator of attack.