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Cisco IOS Multiple GRE Source Routing Vulnerabilities

Cisco IOS is prone to multiple vulnerabilities when decapsulating GRE routing packets.

Specifically, these issues present themselves when the device handles malicious GRE packets with oversized header offset values, and also with malicious GRE packets containing modified source-routing data.

A successful attack can allow an attacker to disclose sensitive information in process memory buffers, bypass security restrictions, deny service to legitimate users, or possibly crash the Cisco IOS operating system.

Cisco IOS 12.0, 12.1, and 12.2 based trains are reported vulnerable. All devices running affected versions of Cisco IOS that are configured with GRE IP or GRE IP multipoint tunnels are vulnerable to this issue.