Adjacent-network code execution via fingerd DHCP overflow
Published Sep 29, 2026 · Updated Sep 29, 2026
Stack-based buffer overflow in WatchGuard Fireware OS allows remote attackers on an adjacent network to execute code or crash fingerd. Its DHCP fingerprinting daemon mishandles a crafted DHCP packet and overwrites a stack buffer; the affected parsing or copy operation is not public. Exploitation requires a network position from which DHCP traffic reaches the Firebox, and the reported outcomes are process termination or code execution.
Summary
What happened
Stack-based buffer overflow in WatchGuard Fireware OS allows remote attackers on an adjacent network to execute code or crash fingerd. Its DHCP fingerprinting daemon mishandles a crafted DHCP packet and overwrites a stack buffer; the affected parsing or copy operation is not public. Exploitation requires a network position from which DHCP traffic reaches the Firebox, and the reported outcomes are process termination or code execution.
The record
- CVE
- CVE-2026-81433
- Published
- Sep 29, 2026
- Updated
- Sep 29, 2026
- Vendor
- WatchGuard Technologies, Inc.
- Product
- Fireware OS
- Classifications
- T1210
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 29, 2026CVE publishedPublication date reported by the CVE source.
- Sep 29, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=12.0 <12.12.3
- Affected versionversion=2025.0 <2026.2.3
- Affected versionversion=2026.3 <2026.3.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Get started to see how Hinoki identifies affected software and validates exploitability in your environment.
Get started