CVE-2026-13374

Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in WatchGuard Fireware OS (ConnectWise Technology Integration module) allows Stored XSS. This vulnerability is an additional unmitigated attack path for CVE-2025-13937.

What this means for your business

It affects Watchguard Fireware. It matters if your company, or a supplier that handles your data, runs it.
An attacker can use it remotely, over a network, with an administrator login, but only after tricking someone into an action such as opening a file or a link.

What to do

1Check whether your company or your suppliers run Watchguard Fireware, and which version. The affected versions are listed further down this page.
2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

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Scoring

CVSS: 4.8 (v3.1)
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
CVSS v4: 4.8
Weakness: CWE-79
Assigned by: 5d1c2695-1a31-4499-88ae-e847036fd7e3

Dates

Published: 2026-07-03
Last modified: 2026-08-28
Sources: NVD

Affected products

Watchguard Fireware12.4 - 12.12.1, 2025.1 - 2026.2.1, 12.5 - 12.5.18
Watchguard Firebox M270all versions
Watchguard Firebox M290all versions
Watchguard Firebox M370all versions
Watchguard Firebox M390all versions
Watchguard Firebox M440all versions
Watchguard Firebox M4600all versions
Watchguard Firebox M470all versions
Watchguard Firebox M4800all versions
Watchguard Firebox M5600all versions
Watchguard Firebox M570all versions
Watchguard Firebox M5800all versions

As listed in the NVD configuration data. Not a statement about your estate.