# CVE-2026-90442: Fireware OS Authenticated Stack Buffer Overflow in certd Allows Denial of Service

Status: published. Published: 2026-10-27. Updated: 2026-11-04.

A stack-based buffer overflow vulnerability in the Fireware OS certd process allows an authenticated attacker with access to the Firebox management interface to crash the certificate management service and potentially execute arbitrary code by sending a specially crafted request.

## Remediation

- fix: Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22 (source: CNA: WatchGuard)

## Affected products and versions

- WatchGuard / Fireware OS: ≥ 2025.1; < 2026.4 (affected, custom); ≥ 12.0; < 12.12.4 (affected, custom). Source: CNA: WatchGuard; platforms: Default
- WatchGuard / Fireware OS: ≥ 12.0; < 12.5.22 (affected, custom). Source: CNA: WatchGuard; platforms: T15/T35

## Severity and prioritization

- CVSS 4.0: 8.6 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L; source: CNA: WatchGuard

- CISA KEV: No listing in collected sources

- EPSS: 0.24% as of 2026-11-04; percentile 15.63%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-121, CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://psirt.watchguard.com/CVE-2026-90442 (CNA: WatchGuard; vendor-advisory)

## Provenance

- CNA: WatchGuard: https://www.cve.org/CVERecord?id=CVE-2026-90442; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-90442; retrieved 2026-11-04; source updated Not reported

Revision: a1acba7d2dc9ca667be09e385e76db712409570a8732d068f4f322ad49bacf80

Canonical: https://y2.dev/cve/CVE-2026-90442

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