WatchGuard Fireware OS up to 12.11.8/2026.1.2 Web UI path traversal

Summaryinfo

A vulnerability marked as critical has been reported in WatchGuard Fireware OS up to 12.11.8/2026.1.2. Impacted is an unknown function of the component Web UI. This manipulation causes path traversal. The identification of this vulnerability is CVE-2026-3987. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical was found in WatchGuard Fireware OS up to 12.11.8/2026.1.2. Affected by this vulnerability is an unknown code of the component Web UI. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A path traversal vulnerability in the Fireware OS Web UI on WatchGuard Firebox systems may allow a privileged authenticated remote attacker to execute arbitrary code in the context of an elevated system process.This issue affects Fireware OS 12.6.1 up to and including 12.11.8 and 2025.1 up to and including 2026.1.2.

The weakness was shared by btaol as wgsa-2026-00009. It is possible to read the advisory at watchguard.com. This vulnerability is known as CVE-2026-3987 since 03/11/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are needed for exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/02/2026). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• WatchGuard

Name

• Fireware OS

Version

• 12.11.0
• 12.11.1
• 12.11.2
• 12.11.3
• 12.11.4
• 12.11.5
• 12.11.6
• 12.11.7
• 12.11.8
• 2026.1.0
• 2026.1.1
• 2026.1.2

License

• commercial

CPE 2.3info

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CPE 2.2info

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