CISCO Security Advisory
Published Date: Not specified
CVE: CVE-2026-20352
Advisory Summary
📅 September 16, 2026
🔔 RISK ALERT: High – Cisco ISE RADIUS DoS (CVE-2026-20352)
➡️ What happened
A vulnerability in the RADIUS feature of Cisco Identity Services Engine (ISE) could allow an unauthenticated remote attacker to trigger a denial of service (DoS) by sending crafted RADIUS requests.
- The affected ISE node may become unavailable.
- In single-node deployments, endpoints that have not already authenticated could lose network access until the node automatically recovers.
- This creates both an availability risk and a potential access-control disruption for enterprise networks, especially where ISE is central to 802.1X, posture, and policy enforcement.
🛠️ Fix availability
✅ Cisco released software updates that address the vulnerability.
🚫 Workarounds
❌ No workarounds are available for this issue.
🧩 Actionable next steps for market professionals
1. Identify affected ISE versions and determine exposure (especially single-node or tightly coupled auth paths).
2. Plan rapid patch deployment to the fixed Cisco ISE software baseline referenced in the advisory.
3. Validate RADIUS traffic paths (ACLs, source restrictions, segmentation) as compensating controls—while noting Cisco states no workarounds exist, these controls can reduce exploit likelihood.
4. Operational contingency planning: ensure monitoring/alerting and recovery procedures are ready to limit downtime impact during an outage condition.
5. Communicate impact window to network, SOC, and identity teams due to potential auth/policy disruption.
- CVE: CVE-2026-20352
- Impact rating: High
- Attack precondition: unauthenticated; remote crafted RADIUS requests
Reference: Vendor Advisory