Improper Input Validation in Cisco IOS XE (CVE‑2018‑0174) Enables DHCP Option 82 Denial‑of‑Service
What It Is – A flaw in the DHCP Option 82 encapsulation code of Cisco IOS and IOS XE allows an unauthenticated attacker to send crafted DHCP packets that trigger a buffer overflow, leading to a denial‑of‑service condition.
Exploitability – Publicly disclosed; proof‑of‑concept code exists. No known active exploits in the wild, but the vulnerability is trivial to trigger on any vulnerable device. CVSS v3.1 base score 7.5 (High).
Affected Products – Cisco IOS Software and Cisco IOS XE Software on routers and switches that implement DHCP Option 82 (all versions prior to the Cisco‑released patches in 2018).
Why It Matters for Trust & Control Assurance
- Control Objective: Ensure the integrity and availability of network‑infrastructure devices through robust configuration and patch‑management controls.
- Continuous monitoring of firmware versions and DHCP traffic provides defensible evidence that devices are not exposed to known DoS vectors.
- Demonstrating timely remediation satisfies multiple framework requirements (e.g., NIST CSF “Protect” and ISO 27001 “Asset Management”) with a single control evidence set.
Recommended Actions
- Verify current IOS/IOS XE version against Cisco’s advisory and apply the security patch immediately.
- Update asset‑inventory records to reflect patched firmware and capture the change as audit evidence.
- Enable logging of DHCP Option 82 events and integrate logs into a SIEM for real‑time anomaly detection.
- Incorporate the patch‑status check into your continuous control‑monitoring workflow.
Source: CISA KEV – CVE‑2018‑0174