CVE-2026-3987
WatchGuard Firebox Arbitrary File Write vis Path Traversal in Fireware Web UI
Description
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.
INFO
Published Date :
April 1, 2026, 10:16 p.m.
Last Modified :
Aug. 14, 2026, 1:30 p.m.
Remotely Exploit :
Yes !
Source :
5d1c2695-1a31-4499-88ae-e847036fd7e3
Affected Products
The following products are affected by CVE-2026-3987
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | 5d1c2695-1a31-4499-88ae-e847036fd7e3 | ||||
| CVSS 4.0 | HIGH | 5d1c2695-1a31-4499-88ae-e847036fd7e3 |
Solution
- Update Fireware OS to a patched version.
- Apply vendor security updates promptly.
- Limit privileged access to the Web UI.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-3987.
| URL | Resource |
|---|---|
| https://psirt.watchguard.com/CVE-2026-3987 | Broken Link |
| https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00009 | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-3987 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-3987
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-3987 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-3987 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Aug. 14, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H Added CPE Configuration AND OR *cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:* versions from (including) 2025.1 up to (excluding) 2026.2 OR cpe:2.3:h:watchguard:firebox_t115-w:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t125:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t125-w:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t145:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t145-w:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t185:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m295:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m395:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m495:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m595:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m695:-:*:*:*:*:*:*:* Added CPE Configuration AND OR *cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:* versions from (including) 12.6.1 up to (excluding) 12.12 OR cpe:2.3:h:watchguard:firebox_t55:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t70:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t20:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t40:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t80:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m440:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m270:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m370:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m470:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m570:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m670:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m290:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m390:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m590:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m690:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m4800:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m5800:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:fireboxv:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m4600:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_m5600:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_nv5:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t25:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t45:-:*:*:*:*:*:*:* cpe:2.3:h:watchguard:firebox_t85:-:*:*:*:*:*:*:* cpe:2.3:a:watchguard:firebox_cloud:-:*:*:*:*:*:*:* Added Reference Type WatchGuard Technologies, Inc.: https://psirt.watchguard.com/CVE-2026-3987 Types: Broken Link Added Reference Type WatchGuard Technologies, Inc.: https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00009 Types: Vendor Advisory -
CVE Modified by 5d1c2695-1a31-4499-88ae-e847036fd7e3
Aug. 10, 2026
Action Type Old Value New Value Changed Affected [{'vendor': 'WatchGuard', 'product': 'Fireware OS', 'versions': [{'status': 'affected', 'version': '12.6.1', 'versionType': 'semver', 'lessThanOrEqual': '12.11.8'}, {'status': 'affected', 'version': '2025.1', 'versionType': 'semver', 'lessThanOrEqual': '2026.1.2'}], 'defaultStatus': 'unaffected'}] [{'vendor': 'WatchGuard', 'product': 'Fireware OS', 'versions': [{'status': 'affected', 'version': '2025.1', 'lessThan': '2026.2', 'versionType': 'custom'}, {'status': 'affected', 'version': '12.6.1', 'lessThan': '12.12', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}] Changed Description 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. 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. Added Reference https://psirt.watchguard.com/CVE-2026-3987 -
CVE Modified by 5d1c2695-1a31-4499-88ae-e847036fd7e3
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'WatchGuard', 'product': 'Fireware OS', 'versions': [{'status': 'affected', 'version': '12.6.1', 'versionType': 'semver', 'lessThanOrEqual': '12.11.8'}, {'status': 'affected', 'version': '2025.1', 'versionType': 'semver', 'lessThanOrEqual': '2026.1.2'}], 'defaultStatus': 'unaffected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-3987', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-04-02T00:00:00+00:00'} -
New CVE Received by 5d1c2695-1a31-4499-88ae-e847036fd7e3
Apr. 01, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-22 Added Reference https://www.watchguard.com/wgrd-psirt/advisory/wgsa-2026-00009