CVE-2026-13371Network attack vector

Authenticated Web UI crash via unsafe deserialization

Published Jul 2, 2026 · Updated Jul 2, 2026

Unsafe deserialization in WatchGuard Fireware OS allows remote authenticated users to crash the Firebox Management Web UI through crafted data. The put_data endpoint deserializes attacker-controlled input without safely rejecting malformed or crafted serialized data. Affected releases are 12.0 through 12.12, 12.5 through 12.5.18, and 2025.1 through 2026.2; administrator privileges are required, and the reported consequence is limited to a Web UI crash.

CVSS severityUnavailable
Unscored
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Unsafe deserialization in WatchGuard Fireware OS allows remote authenticated users to crash the Firebox Management Web UI through crafted data. The put_data endpoint deserializes attacker-controlled input without safely rejecting malformed or crafted serialized data. Affected releases are 12.0 through 12.12, 12.5 through 12.5.18, and 2025.1 through 2026.2; administrator privileges are required, and the reported consequence is limited to a Web UI crash.

The record

CVE
CVE-2026-13371
Published
Jul 2, 2026
Updated
Jul 2, 2026
Vendor
WatchGuard Technologies
Product
Fireware OS
Classifications
T1499
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jul 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 2, 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. Affected versionversion=12.5 <=12.5.18
  3. Affected versionversion=2025.1 <=2026.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

WatchGuard Technologies · Fireware OSversion=12.0 <=12.12; version=12.5 <=12.5.18; version=2025.1 <=2026.2

Published CVSS scores

No CVSS assessment is available in this record.

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.

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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