Overview Table
| CVE ID | Type | Affected Component | Impact | CVSS v3.1 |
|---|---|---|---|---|
| CVE‑2025‑40779 | Assertion Failure / Denial of Service | Kea DHCPv4 (kea-dhcp4 process) | Remote crash of DHCP service via crafted unicast packet | 7.5 (High) X (formerly Twitter)+5NVD+5cvetodo.com+5security.paloaltonetworks.com+4kb.isc.org+4Dbugs+4 |
Deep Dive Analysis
- Root Cause:
The DHCPv4 server (kea-dhcp4) aborts due to an assertion failure when it receives a unicast request containing certain options and fails to match it to a configured subnet. Broadcast messages do not trigger this issue GitHub+4NVD+4cvetodo.com+4. - Affected Versions:
Kea DHCP versions 2.7.1 through 2.7.9, as well as 3.0.0 and 3.1.0, are vulnerable X (formerly Twitter)+5kb.isc.org+5cvetodo.com+5. - Exploit Vector:
Network-based, low complexity, no privileges or user interaction required security.paloaltonetworks.com+3cvetodo.com+3GitHub+3. - Severity and Impact:
Denial-of-Service—attackers can crash the DHCP service with a single crafted unicast packet, severely impacting network availability learn.microsoft.com+12kb.isc.org+12cvetodo.com+12.
CyberDudeBivash Impact Analysis & Action Plan
Attack Surface & Risk Context
- Unauthenticated remote DoS.
- Affects core network infrastructure responsible for dynamic IP assignment.
- High risk in enterprise and production environments where DHCP uptime is critical.
Mitigation Strategy
- Immediate Upgrade to patched versions (e.g., Kea 3.0.1 and 3.1.1 or beyond) — ensure deployment across all affected systems security.paloaltonetworks.com+10kb.isc.org+10NVD+10.
- Restrict Unicast Requests: Configure network controls or firewall rules to limit or vet unicast DHCP traffic, especially from untrusted sources.
- Enable DHCP Redundancy/Failover: Ensure DHCP availability even if one instance crashes by implementing high-availability or backup mechanisms.
- Logging & Monitoring: Track DHCP crash events and suspicious unicast request patterns for early detection.
- Vendor Communication: Engage with ISC support channels if unpatched systems must remain live.
Strategic Insight
This is a classic example of how edge-case input handling in critical network services can lead to catastrophic failures. Even a single malformed or unexpected DHCP packet can disrupt entire network segments. Proactive patching and robust architectural hardening are non-negotiable.
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