Overview
The CVE-2025-20189 vulnerability is a significant flaw in the Cisco Express Forwarding functionality of the Cisco IOS XE Software for Cisco ASR 903 Aggregation Services Routers with Route Switch Processor 3 (RSP3C). This vulnerability can be exploited by an unauthenticated, adjacent attacker to trigger a denial of service (DoS) condition, potentially compromising the system or leading to data leakage.
Vulnerability Summary
CVE ID: CVE-2025-20189
Severity: High (7.4 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Successful exploitation could allow the attacker to exhaust system resources, causing a reload of the active route switch processor (RSP). In the absence of a redundant RSP, the router reloads, potentially leading to system compromise or data leakage.
Affected Products
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Product | Affected Versions
Cisco IOS XE Software for Cisco ASR 903 Aggregation Services Routers with Route Switch Processor 3 (RSP3C) | All versions prior to patch
How the Exploit Works
The exploit works by sending crafted ARP messages at a high rate over a period of time to an affected device. This triggers a vulnerability in the Cisco Express Forwarding functionality of the Cisco IOS XE Software due to improper memory management. This in turn allows an attacker to exhaust system resources, leading to a reload of the active route switch processor (RSP). If a redundant RSP is not present, the router reloads, leading to a DoS condition.
Conceptual Example Code
While the exact code used to exploit this vulnerability is not available, an attacker might use a tool to send a large number of ARP messages to the target device. This could be conceptually represented by the pseudocode below:
for i in range(1, 1000000):
send_arp("target_ip_address", crafted_arp_message)In this example, `send_arp` is a hypothetical function that sends an ARP message to a target IP address, and `crafted_arp_message` is a malicious ARP message crafted to exploit the vulnerability.