CVE-2026-78011Network attack vector

Unauthenticated VPN interruption via iked integer underflow

Published Aug 27, 2026 · Updated Aug 27, 2026

Integer underflow in the iked process in WatchGuard Fireware OS allows remote attackers to interrupt VPN processing with crafted traffic. WatchGuard maps the flaw to an out-of-bounds write but does not publish the affected function, packet field, or arithmetic path. No authentication or user interaction is required, and the published impact is limited to VPN-processing availability.

CVSS severity8.7
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in the iked process in WatchGuard Fireware OS allows remote attackers to interrupt VPN processing with crafted traffic. WatchGuard maps the flaw to an out-of-bounds write but does not publish the affected function, packet field, or arithmetic path. No authentication or user interaction is required, and the published impact is limited to VPN-processing availability.

The record

CVE
CVE-2026-78011
Published
Aug 27, 2026
Updated
Aug 27, 2026
Vendor
WatchGuard Technologies, Inc.
Product
Fireware OS
Classifications
CWE-191, CWE-787, T1499.004
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

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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

8.7WatchGuard Technologies, Inc.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

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-191Integer Underflow (Wrap or Wraparound)
CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

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

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Your stack

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