CVE-2025-20149 in IOS
Summary
by MITRE • 09/24/2025
A vulnerability in the CLI of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, local attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition.
This vulnerability is due to a buffer overflow. An attacker with a low-privileged account could exploit this vulnerability by using crafted commands at the CLI prompt. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.
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Analysis
by VulDB Data Team • 09/24/2025
This vulnerability represents a critical buffer overflow flaw in the command line interface of Cisco IOS and IOS XE software platforms, specifically affecting devices running these operating systems. The issue stems from inadequate input validation within the CLI processing mechanism, where maliciously crafted commands can exceed allocated buffer boundaries and overwrite adjacent memory segments. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which describes heap-based buffer overflow conditions that can lead to arbitrary code execution or system instability. The vulnerability is particularly concerning because it requires only low-privileged authentication to exploit, making it accessible to attackers who have gained basic access to the device through legitimate means such as SSH or console connections.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can be leveraged to create persistent disruptions in network infrastructure. When exploited successfully, the buffer overflow causes the affected device to crash and reload unexpectedly, potentially leading to cascading failures throughout the network topology. Network administrators may experience service interruptions that could affect critical communications, especially in environments where these devices serve as core routing or switching points. The vulnerability's exploitation vector through the CLI interface means that even users with limited privileges can trigger this condition, making it particularly dangerous in multi-tenant environments or when default administrative accounts remain active. This scenario aligns with ATT&CK technique T1059.004 for Command and Scripting Interpreter, where adversaries can leverage legitimate system access to execute malicious commands that trigger system instability.
Mitigation strategies should focus on immediate patch deployment from Cisco, as the vendor has likely released security advisories addressing this specific buffer overflow condition. Network security teams must implement comprehensive monitoring of CLI access patterns to detect anomalous command sequences that might indicate exploitation attempts. Additionally, implementing least privilege access controls and disabling unnecessary administrative accounts can significantly reduce the attack surface. The vulnerability highlights the importance of input validation and memory safety practices in network device software development, emphasizing the need for regular security assessments and code reviews. Organizations should also consider implementing network segmentation to limit the potential impact of successful exploitation, ensuring that a single compromised device cannot cause widespread network disruption. Regular security training for network administrators regarding the identification of suspicious CLI activities remains crucial in maintaining overall network resilience against such threats.