WatchGuard Firebox Out-of-Bounds Write Vulnerability (CVE-2025-9242)

WatchGuard Firebox contains an out-of-bounds write vulnerability in the OS iked process that may allow a remote unauthenticated attacker to execute arbitrary code.

Published Sep 17, 2025 · Updated May 29, 2026

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Why patchRisk explained in plain English

Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2025-12-03 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Out-of-bounds Write (CWE-787) vulnerability in WatchGuard Firebox. An Out-of-bounds Write vulnerability in WatchGuard Fireware OS may allow a remote unauthenticated attacker to execute arbitrary code. This vulnerability affects both the Mobile User VPN with IKEv2 and the Branch Office VPN using IKEv2 when configured with a dynamic gateway peer.This vulnerability affects Fireware OS 11.10.2 up to and including 11.12.4_Update1, 12.0 up to and including 12.11.3 and 2025.1. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

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Phishing link

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Malicious file

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Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

●IT Security

●Running fireware: 11.10.2 ≤ v < 12.11.4, 11.10.2 ≤ v < 12.5.13, 2025.1

Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: https://github.com/watchtowrlabs/watchTowr-vs-WatchGuard-CVE-2025-9242/blob/main/watchTowr-vs-WatchGuard-CVE-2025-9242.py

How to patch

Get the fix

Apply the fixed package from your vendor. The advisory lists affected versions and the exact fixed build.

↗ Vendor advisory

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.