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WatchGuard Fireware OS EUVDEUVD-2026-67337

| CVE-2026-19317 HIGH
Out-of-bounds Read (CWE-125)
2026-08-27 WatchGuard GHSA-fj8p-qfhx-jffx
8.7
CVSS 4.0 · Vendor: WatchGuard
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Identify WatchGuard appliance IKE listener on UDP 500/4500
  2. Delivery
    Craft malformed IKE negotiation packet with out-of-bounds payload
  3. Exploit
    Send packet to iked process unauthenticated
  4. Execution
    Trigger OOB read causing iked process crash
  5. Impact
    VPN service unavailable, all tunnels dropped

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

No special conditions are required beyond network reachability to the iked VPN listener: exploitation is unauthenticated, requires no prior session state, and targets the default IKE service (UDP 500/4500) that must be externally reachable for any IPsec VPN to function. Limiting factors include: the appliance must have the iked process running and the VPN listener exposed on a reachable interface, and exploitation results only in a DoS (availability) impact - there is no confirmed code execution or confidentiality breach from this flaw alone. Organizations that do not use WatchGuard IPsec VPN or have the iked listener blocked from untrusted networks are not exposed.

Impact

The CVSS 4.0 score of 8.7 with vector AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N reflects a network-accessible, low-complexity, unauthenticated DoS with high availability impact on the vulnerable component and no scope change. The signals are largely consistent: no elevated privileges, no user interaction, and direct network reachability to the iked VPN listener. The risk is high for organizations relying on WatchGuard IPsec VPNs - a successful exploit disrupts VPN connectivity entirely, which is operationally severe for remote-access or site-to-site deployments. No EPSS data was provided in the source intelligence. No CISA KEV listing exists, and no public exploit code has been identified, which moderates near-term mass exploitation probability. However, the zero-prerequisite attack profile (unauthenticated, network, low complexity) means exploitation is straightforward once a PoC is developed. The 'Information Disclosure' tag warrants attention: CWE-125 OOB reads can leak heap or stack memory in addition to crashing, but CVSS explicitly sets VC:N - this discrepancy should be verified against the full WatchGuard advisory at https://psirt.watchguard.com/CVE-2026-19317.

Exploit ScenarioDerived

An attacker with network access to the WatchGuard appliance's IKE listener sends a single malformed IKE negotiation packet containing a crafted payload that triggers an out-of-bounds read in the iked process, causing it to crash and terminating all active and pending VPN sessions. No authentication or prior session state is required, and the low complexity means the attack can be scripted and sent repeatedly to maintain a persistent DoS condition. No public PoC has been identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 28, 2026

Out-of-bounds read in the WatchGuard Fireware OS iked (Internet Key Exchange daemon) process enables remote unauthenticated attackers to crash VPN processing by sending specially crafted network traffic, resulting in a Denial of Service condition. All Fireware OS versions appear affected per the wildcard CPE, and the vulnerability is reachable without authentication from any network path to the iked listener. No public exploit code or CISA KEV listing has been identified at time of analysis, but the low attack complexity makes this a realistic target for disrupting VPN availability on WatchGuard appliances.

RemediationAI

The primary remediation is to apply the vendor-released patch from WatchGuard once available; consult the PSIRT advisory at https://psirt.watchguard.com/CVE-2026-19317 for exact patched version numbers, as none were specified in the available intelligence. Until patching is complete, restrict inbound IKE traffic (UDP 500 and UDP 4500, used for IKE and NAT-T respectively) to known trusted IP addresses or VPN peers using upstream firewall rules or WatchGuard policy - this directly limits the attacker's ability to reach the iked listener. If the VPN service is not required on the exposed interface, disable the iked service or the relevant VPN configuration profiles to eliminate the attack surface entirely; note this disrupts all IPsec VPN tunnels on the affected interface. For perimeter-deployed appliances where IKE cannot be filtered, consider temporarily routing VPN traffic through an intermediate gateway that can validate IKE packet structure before forwarding. Monitor iked process health and restart policies, as crashes will interrupt VPN availability.

Affected VersionsENISA

Fireware OS 12.0 <12.12.2
Fireware OS 2025.0 <2026.2.2
Fireware OS 12.0 <12.5.20

Affected Packages

euvd fireware_os fix: 12.5.20, 12.12.2, 2026.2.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The iked process in WatchGuard Fireware OS implements the IKE (Internet Key Exchange) protocol used for IPsec VPN tunnel negotiation. CWE-125 (Out-of-Bounds Read) indicates the process reads beyond the bounds of an allocated buffer when parsing incoming IKE/VPN traffic, likely during packet parsing or payload processing. This class of flaw in network-facing daemons typically results from insufficient length validation of attacker-controlled fields before dereferencing a pointer or indexing into a buffer. The affected CPE (cpe:2.3:a:watchguard:fireware_os:*:*:*:*:*:*:*:*) uses a wildcard version, indicating no specific version range has been bounded - meaning all Fireware OS releases should be treated as potentially affected until the vendor advisory specifies otherwise. Tags include 'Information Disclosure,' consistent with OOB reads potentially leaking adjacent memory contents, though the CVSS 4.0 vector explicitly shows VC:N, suggesting confirmed confidentiality impact has not been demonstrated.

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Severity by source

Vendor (WatchGuard) PRIMARY 8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
vuln.today AI 7.5 HIGH

Network-reachable unauthenticated IKE listener crash; pure availability impact, no scope change, no confidentiality or integrity effect confirmed.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (WatchGuard).

CVSS VectorVendor: WatchGuard

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

2
Patch available
Aug 28, 2026 - 04:16 EUVD
CVE Published
Aug 27, 2026 - 23:24 cve.org
HIGH 8.7

DescriptionCVE.org

An out-of-bounds read vulnerability in the WatchGuard Fireware OS iked process allows a remote unauthenticated attacker to create a Denial of Service (DoS) condition in VPN processing by sending specially crafted network traffic.

Executive ViewAI

Why It Matters

A critical vulnerability in WatchGuard Fireware OS iked daemon allows unauthenticated remote attackers to crash VPN services with no public exploit identified at time of analysis, though low attack complexity makes exploitation a realistic risk. All Fireware OS versions are affected, with no vendor patch currently available, creating immediate business continuity risk for organizations dependent on WatchGuard VPN appliances. This directly threatens workforce connectivity and remote access-foundational enterprise capabilities-requiring urgent mitigation action.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations include: (1) Network segmentation restricting iked listener access to trusted networks only; (2) Rate-limiting and traffic filtering rules on iked ports to block suspicious patterns; (3) Redundant VPN appliances with automatic failover to maintain availability during attacks; (4) Real-time monitoring and alerting for iked process crashes and anomalous traffic patterns.

Threat Intelligence Overview

EPSS Score
0.3%
Top 76% exploitable
Prevalence
Medium
popular SMB/mid-market network security appliance vendor
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
High
Technical Impact
Partial

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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