How severe is CVE-2026-3987?

CVE-2026-3987 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-3987 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-3987?

CVE-2026-3987 affects Watchguard Fireware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-3987?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-3987 have an EU (EUVD) identifier?

Yes. CVE-2026-3987 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18090.

When was CVE-2026-3987 published?

CVE-2026-3987 was published on 2026-04-01 and last updated on 2026-08-14.

CVE-2026-3987

CVE-2026-3987 is a high-severity vulnerability in Watchguard Fireware with a CVSS 3.x base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

Severity: High (CVSS 3.x base score 7.2)
CVSS v4: 8.6
EPSS exploit prediction: 1% (63rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-18090
Weakness: CWE-22
Affected product: Watchguard Fireware
Published: 2026-04-01
Last modified: 2026-08-14

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.

Frequently asked questions

What is CVE-2026-3987?: 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.
How severe is CVE-2026-3987?: CVE-2026-3987 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-3987 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-3987?: CVE-2026-3987 affects Watchguard Fireware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-3987?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-3987 have an EU (EUVD) identifier?: Yes. CVE-2026-3987 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-18090.
When was CVE-2026-3987 published?: CVE-2026-3987 was published on 2026-04-01 and last updated on 2026-08-14.

References

Affected products (1)

cpe:2.3:o:watchguard:fireware:*:*:*:*:*:*:*:*

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