CVE-2026-13376
Received Received - Intake

Stored XSS in WatchGuard Fireware OS SpamBlocker Module

Publication date: 2026-07-03

Last updated on: 2026-07-03

Assigner: WatchGuard Technologies, Inc.

Description
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in WatchGuard Fireware OS spamBlocker module allows Stored XSS. This vulnerability is an additional unmitigated attack path for CVE-2025-1071. This issue affects Fireware OS 12.0 up to and including 12.12, 12.5 up to and including 12.5.18, and 2025.1 up to and including 2026.2.

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Meta Information

Published
2026-07-03
Last Modified
2026-07-03
Generated
2026-07-03
AI Q&A
2026-07-03
EPSS Evaluated
N/A
NVD
CVE-2026-13376
EUVD
EUVD-2026-41451

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
watchguard fireware_os to 12.12 (inc)
watchguard fireware_os to 12.5.18 (inc)
watchguard fireware_os to 2026.2 (inc)

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Attack-Flow Graph

AI Quick Actions

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Mitigation Strategies

To mitigate the stored Cross-Site Scripting (XSS) vulnerability in the spamBlocker module of WatchGuard Firebox devices, you should upgrade your Fireware OS to the fixed versions.

  • Upgrade to Fireware OS 2026.2.1 if you are running the 2025.1 branch.
  • Upgrade to Fireware OS 12.12.1 if you are running the 12.x branch.

Note that some 12.5.x models (specifically T15 & T35) remain unresolved, so verify your device model and consider additional mitigations or vendor guidance.

Compliance Impact

The provided information does not specify how the CVE-2026-13376 vulnerability impacts compliance with common standards and regulations such as GDPR or HIPAA.

Executive Summary

CVE-2026-13376 is a stored Cross-Site Scripting (XSS) vulnerability found in the spamBlocker module of WatchGuard Firebox devices running certain versions of Fireware OS. It occurs due to improper neutralization of input during web page generation, which allows attackers to inject malicious scripts that are stored and later executed in the context of a user's browser.

Impact Analysis

This vulnerability can allow attackers to execute malicious scripts in the context of the affected device's web interface, potentially leading to unauthorized actions, data theft, or session hijacking. Since it is a stored XSS, the malicious code can persist and affect multiple users who access the vulnerable interface. The impact is considered medium with a CVSS score of 4.8.

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