CVE-2026-19318Network attack vector

Pre-authentication code execution via IKE_AUTH length underflow

Published Aug 27, 2026 · Updated Aug 27, 2026

Stack-based buffer overflow in WatchGuard Fireware OS allows remote attackers to execute code through a crafted IKE_AUTH message. An undersized embedded length in an EAP-MSCHAPv2 payload underflows an array index and causes an attacker-influenced stack overwrite in iked. The path requires completed IKE_SA_INIT, an IKEv2 Mobile VPN or Branch Office VPN configuration, and enabled IKE payload diagnostic logging; exploitation crashes and automatically respawns iked, while the overwrite permits code execution.

CVSS severity9.3
Critical
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stack-based buffer overflow in WatchGuard Fireware OS allows remote attackers to execute code through a crafted IKE_AUTH message. An undersized embedded length in an EAP-MSCHAPv2 payload underflows an array index and causes an attacker-influenced stack overwrite in iked. The path requires completed IKE_SA_INIT, an IKEv2 Mobile VPN or Branch Office VPN configuration, and enabled IKE payload diagnostic logging; exploitation crashes and automatically respawns iked, while the overwrite permits code execution.

The record

CVE
CVE-2026-19318
Published
Aug 27, 2026
Updated
Aug 27, 2026
Vendor
WatchGuard Technologies, Inc.
Product
Fireware OS
Classifications
CWE-121, CWE-129, CWE-191, CAPEC-8, CAPEC-100, CAPEC-47, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=12.0 <12.12.2
  2. Affected versionversion=12.0 <12.5.20
  3. Affected versionversion=2025.0 <2026.2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WatchGuard Technologies, Inc. · Fireware OSversion=12.0 <12.12.2; version=12.0 <12.5.20; version=2025.0 <2026.2.2

Published CVSS scores

9.3WatchGuardCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-129Improper Validation of Array Index
CWE-191Integer Underflow (Wrap or Wraparound)
CAPEC-8Buffer Overflow in an API Call
CAPEC-100Overflow Buffers
CAPEC-47Buffer Overflow via Parameter Expansion
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo