Cisco has recently identified a significant security vulnerability within its IOS and IOS XE Software, designated as CVE-2025-20352, carrying a CVSS score of 7.7. This flaw resides in the Simple Network Management Protocol (SNMP) subsystem and has been actively exploited in the wild. The company became aware of this issue following incidents where local Administrator credentials were compromised.
Understanding the Vulnerability
The core of this vulnerability is a stack overflow condition within the SNMP subsystem. An authenticated, remote attacker can exploit this flaw by dispatching a specially crafted SNMP packet to an affected device over both IPv4 and IPv6 networks. The consequences of such an attack vary based on the attacker’s privilege level:
– Denial-of-Service (DoS): Attackers with low-level privileges can cause the device to reload unexpectedly, leading to a DoS condition.
– Remote Code Execution (RCE): Attackers with higher privileges can execute arbitrary code as the root user, potentially gaining full control over the compromised system.
Conditions for Exploitation
For an attacker to successfully exploit this vulnerability, specific conditions must be met:
1. To Induce DoS:
– The attacker must possess the SNMPv2c (or earlier) read-only community string or valid SNMPv3 user credentials.
2. To Achieve RCE:
– The attacker must have the SNMPv1 or v2c read-only community string or valid SNMPv3 user credentials.
– Additionally, the attacker must have administrative or privilege 15 credentials on the affected device.
Affected Systems
This vulnerability impacts all versions of SNMP. Notably, devices such as the Meraki MS390 and Cisco Catalyst 9300 Series Switches running Meraki CS 17 and earlier are susceptible. However, Cisco IOS XR Software and NX-OS Software remain unaffected.
Mitigation and Recommendations
Cisco has addressed this vulnerability in the IOS XE Software Release 17.15.4a. While no direct workarounds exist, the following mitigations are advised:
– Restrict SNMP Access: Ensure that only trusted users have SNMP access to the affected systems.
– Monitor SNMP Configurations: Regularly review SNMP configurations using commands like `show snmp host` to detect unauthorized changes.
– Disable Affected OIDs: Administrators can disable specific Object Identifiers (OIDs) on devices. It’s essential to note that not all software supports the OID listed in the mitigation. If the OID isn’t valid for specific software, it’s not affected by this vulnerability. However, excluding these OIDs may impact device management through SNMP, such as discovery and hardware inventory.
Broader Implications
This vulnerability underscores the critical importance of robust SNMP configurations and vigilant monitoring. SNMP, while essential for network management, can become a vector for attacks if not properly secured. Organizations are urged to:
– Regularly Update Software: Ensure that all devices run the latest software versions to benefit from security patches.
– Limit SNMP Exposure: Configure SNMP to accept requests only from trusted IP addresses and limit the use of default community strings.
– Implement Strong Authentication: Utilize SNMPv3, which offers enhanced security features, including authentication and encryption.
Conclusion
The discovery and active exploitation of CVE-2025-20352 serve as a stark reminder of the evolving threat landscape. Organizations must adopt a proactive approach to network security, emphasizing timely updates, stringent access controls, and continuous monitoring to safeguard against such vulnerabilities.
