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PASSEDnetwork / ssl_vpn_overwhelmed
SSL VPN Concentrator Overwhelmed — Max Sessions
A sudden work-from-home mandate floods the SSL VPN concentrator with 500+ simultaneous connections. The device supports 250 concurrent sessions. Users see 'maximum sessions reached' errors. Split tunneling not configured, so all traffic routes through VPN, crushing the bandwidth.
Pattern
FORTINET_EVENT
Severity
CRITICAL
Confidence
95%
Remediation
Remote Hands
Test Results
| Metric | Expected | Actual | Result |
|---|---|---|---|
| Pattern Recognition | FORTINET_EVENT | FORTINET_EVENT | |
| Severity Assessment | CRITICAL | CRITICAL | |
| Incident Correlation | Yes | 24 linked | |
| Cascade Escalation | N/A | No | |
| Remediation | — | Remote Hands — Corax contacts on-site support via call, email, or API |
Scenario Conditions
Fortinet FortiGate 200F as SSL VPN concentrator. Licensed for 250 concurrent sessions. 500+ users attempting to connect. Full tunnel mode (no split tunnel). 500Mbps internet uplink at HQ. Average per-user bandwidth: 5Mbps.
Injected Error Messages (2)
FortiGate SSL VPN max sessions reached — 250/250 concurrent tunnels active, 278 users in queue receiving 'maximum login session reached' error, FortiClient timeout on connection, Fortinet SSL VPN session table full, CPU at 94% from encryption overhead
HQ internet uplink saturated by FortiGate VPN traffic — 500Mbps link at 98% utilization, full-tunnel VPN routing all remote user traffic through HQ, internet browsing for on-site users degraded to <5Mbps, Fortinet QoS queues dropping packets
Neural Engine Root Cause Analysis
The FortiGate SSL VPN has reached its maximum concurrent session limit of 250 tunnels with 278 additional users queued, causing new connection attempts to fail. The high CPU utilization at 94% is primarily due to encryption overhead from handling the maximum number of active SSL VPN sessions. This is a capacity exhaustion issue rather than a service failure - the VPN gateway is functioning but cannot accept new connections due to licensing or configuration limits.
Remediation Plan
1. Immediately check for idle or stale VPN sessions that can be terminated to free up slots. 2. Review VPN session timeout settings to ensure inactive sessions are purged appropriately. 3. Identify if any users have multiple concurrent sessions and consolidate where possible. 4. Evaluate current VPN licensing to determine if session limit can be increased. 5. Consider implementing connection prioritization or load balancing across multiple VPN gateways. 6. Monitor user connection patterns to plan for capacity expansion during peak usage periods.
Tested: 2026-03-30Monitors: 2 | Incidents: 2Test ID: cmncjl7bo02cwobqed3ouddnl