RCE-capable stack buffer overflow in a widely deployed firewall OS component could enable device takeover, traffic interception, and broad network disruption.
CVE-2026-81433
Stack buffer overflow in WatchGuard Fireware DHCP fingerprinting allows adjacent RCE or crash.
Is CVE-2026-81433 being exploited?
Not confirmed. CVE-2026-81433 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked.
How severe is CVE-2026-81433?
CVE-2026-81433 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-81433?
Not known from our data. No patch reference has been recorded for CVE-2026-81433, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-81433 affect?
CVE-2026-81433 affects WatchGuard Fireware OS (fingerd DHCP fingerprinting daemon), WatchGuard firewall appliances running Fireware. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-81433?
Isolate affected appliances, block/limit DHCP from untrusted networks, apply vendor patch when released.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated adjacent attacker can send crafted DHCP packets to trigger a stack overflow in fingerd, enabling remote code execution or crash and potential firewall takeover.
Immediate action required
- affected>= 2026.3 and < 2026.3.2
- affected>= 2025.0 and < 2026.2.3
- affected>= 12.0 and < 12.12.3
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.