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This vulnerability exploits a logic flaw within the “Reject RADIUS requests from clients with repeated failures” feature on Cisco ISE. The issue occurs when the system processes a RADIUS Access-Request for a MAC address that is already flagged in the rejected endpoints cache. A specific sequence of crafted RADIUS packets targeting such a MAC address triggers an error condition that the software cannot handle gracefully. This error leads to an uncontrolled resource consumption or a critical process crash, forcing the entire ISE application to restart unexpectedly. The restart causes a complete denial of service, disrupting all network authentication services provided by the ISE platform until the system fully recovers. The attack is unauthenticated and can be performed remotely by sending the malicious packet sequence to the ISE RADIUS service port.
Platform: Cisco ISE
Version: Affected Versions
Vulnerability: Logic Error
Severity: Critical
date: 2025-11-05
Prediction: Patch by 2025-12-15
What Undercode Say:
`radiusd -X`
`show logging application ise-process-radius`
`debug radius platform detail`
`show endpoint reject-history mac `
How Exploit:
Craft RADIUS Access-Request packets for a known rejected MAC address and send them in a rapid, specific sequence to the ISE server’s RADIUS port, triggering the flawed logic and causing a service restart.
Protection from this CVE:
Apply Cisco patch. Temporarily disable the “Reject RADIUS requests from clients with repeated failures” feature if possible. Implement network ACLs to restrict RADIUS client source IPs.
Impact:
Denial of Service, complete ISE service restart, disruption of network authentication.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
