A high-severity vulnerability has been discovered in the Simple Network Management Protocol (SNMP) subsystem of widely-used Cisco networking software. An authenticated attacker with low-level privileges can remotely exploit this flaw to cause a device to crash, resulting in a Denial of Service (DoS) and a network outage. Organizations should prioritize applying security updates to prevent disruption to critical network infrastructure.

The vulnerability exists within the SNMP service of Cisco IOS and IOS XE software. A remote attacker who has successfully authenticated to an affected device with low-privilege credentials can exploit this flaw by sending a specially crafted SNMP request. The processing of this malicious request triggers an unhandled condition, leading to a crash of the SNMP process and a subsequent device reload, causing a complete Denial of Service (DoS).

This vulnerability is rated as High severity with a CVSS score of 7.7. The primary business impact is the potential for significant network disruption. Successful exploitation will lead to a Denial of Service, causing network devices like routers and switches to become unresponsive or reboot. This can result in widespread connectivity loss for users, applications, and critical services, leading to operational downtime, productivity loss, and potential financial impact. The risk is elevated as the attacker only requires low-privilege authenticated access, which may be more common or less monitored than administrative accounts.

Immediate Action: Apply the security updates provided by Cisco to all affected devices immediately. Prioritize patching for internet-facing systems and critical internal infrastructure. After patching, continue to monitor for any signs of exploitation attempts and review device and authentication logs for suspicious activity.

Proactive Monitoring: Security teams should monitor for anomalous SNMP traffic, such as an unusual volume of requests or queries from non-standard IP addresses. Monitor device logs for SNMP-related errors or repeated process crashes. Keep a close watch on CPU and memory utilization on critical devices, as abnormal spikes could indicate an attempted or successful attack.

Compensating Controls: If immediate patching is not feasible, implement the following controls to mitigate risk:

• Use Access Control Lists (ACLs) to restrict SNMP access to a limited set of trusted and authorized management workstations.
• Disable the SNMP service on any device where it is not mission-critical.
• Ensure all user accounts, including those with low privileges, have strong, unique passwords and are regularly audited.

Public Exploit Available: False

This vulnerability poses a significant risk to network availability and should be addressed urgently. We recommend that organizations prioritize the deployment of vendor-supplied patches across all affected Cisco IOS and IOS XE devices. While this CVE is not currently on the CISA KEV list, its high CVSS score and the widespread deployment of affected devices make it a prime target for future exploitation. In addition to patching, organizations should implement the recommended compensating controls, particularly SNMP access restrictions, as a standard security practice to strengthen their defense-in-depth posture.