CVE-2025-20149 is a buffer overflow vulnerability identified in the command-line interface (CLI) of Cisco IOS and Cisco IOS XE software. This vulnerability arises due to improper handling of input sizes during buffer copy operations, allowing an authenticated local attacker with low privileges to exploit crafted CLI commands. Successful exploitation results in a buffer overflow that causes the affected Cisco device to reload unexpectedly, leading to a denial of service (DoS) condition. The vulnerability affects a wide range of Cisco IOS versions, spanning numerous releases primarily in the 15.x series, indicating a long-standing and broadly deployed issue. The attack vector requires local authentication but does not require user interaction beyond command execution. The vulnerability impacts availability exclusively, with no direct confidentiality or integrity compromise reported. The CVSS v3.1 base score is 6.5 (medium severity), reflecting the low complexity of exploitation (low attack complexity), the requirement for low privileges, and the significant impact on availability. No known exploits are currently reported in the wild, and no patches or mitigations are explicitly linked in the provided data, suggesting organizations must proactively monitor Cisco advisories for updates. This vulnerability is a classic buffer overflow, a common and well-understood software flaw, but its presence in critical network infrastructure software like Cisco IOS elevates its importance due to the potential disruption of network operations.

For European organizations, the impact of CVE-2025-20149 could be significant, especially for those relying heavily on Cisco network infrastructure for critical operations. The vulnerability enables an authenticated attacker with low privileges to cause device reloads, resulting in network outages or degraded service availability. This can disrupt business continuity, impact service-level agreements, and potentially affect critical sectors such as finance, telecommunications, healthcare, and government services. Since the vulnerability requires local authentication, the risk is heightened in environments where internal threat actors or compromised credentials exist. The broad range of affected IOS versions implies many legacy and current devices may be vulnerable, increasing the attack surface. Additionally, the scope of affected systems includes routers and switches that form the backbone of enterprise and service provider networks, meaning exploitation could have cascading effects on network stability and security monitoring capabilities. Although no confidentiality or integrity impacts are reported, the availability disruption alone can have severe operational and reputational consequences for European entities.

1. Immediate inventory and identification of Cisco IOS and IOS XE devices running affected versions within the network. 2. Restrict CLI access strictly to trusted administrators and enforce strong authentication mechanisms, including multi-factor authentication, to reduce the risk of unauthorized local access. 3. Monitor and audit CLI access logs for unusual or unauthorized command execution attempts. 4. Apply Cisco-released patches or updates as soon as they become available; maintain close communication with Cisco security advisories for timely updates. 5. Implement network segmentation to isolate critical network devices and limit the potential impact of a compromised local account. 6. Employ role-based access control (RBAC) to minimize privileges granted to users, ensuring that low-privileged accounts cannot execute commands that trigger the vulnerability. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) that can detect anomalous CLI command patterns or device reload events. 8. Develop and test incident response plans specifically addressing network device DoS scenarios to ensure rapid recovery and minimal downtime.