Cisco IOS XE Software Simple Network Management Protocol Denial of Service Vulnerability

TL;DR 📌

A denial of service (DoS) vulnerability has been identified in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software. An authenticated remote attacker can exploit this vulnerability to cause affected devices to reload unexpectedly. The highest CVSS score for this vulnerability is 7.7, categorized as High severity. Cisco has released software updates to address this issue, but there are no workarounds available.

What happened 🕵️‍♂️

A vulnerability in the SNMP subsystem of Cisco IOS XE Software allows an authenticated remote attacker to send a specific SNMP request that can lead to a denial of service condition. This occurs due to improper error handling when processing the request, potentially causing the device to reload unexpectedly. The vulnerability affects SNMP versions 1, 2c, and 3, with different exploitation requirements based on the version used.

Affected products 🖥️

This vulnerability affects Cisco switches running a vulnerable release of Cisco IOS XE Software with the weighted early random detection (WRED) for Multiprotocol Label Switching (MPLS) experimental field configured and SNMP enabled. Cisco routing platforms running IOS XE Software are not affected.

Fixed software 🔧

Upgrade to the first fixed release in your train (or later):

Workarounds 🧯

There are no workarounds that fully address this vulnerability. However, as a mitigation step, administrators can disable the affected object identifier (OID) on the device. It is recommended that SNMP access be restricted to trusted network devices.

Risk in context 🎯

With a CVSS score of 7.7, this vulnerability is rated as High risk. The exposure requires authenticated access, meaning that an attacker must know a valid SNMP community string or have valid SNMP user credentials. The potential for denial of service could impact device availability, making it critical for affected organizations to apply the necessary patches promptly.

Fast facts ⚡

• Vulnerability: SNMP Denial of Service
• CVSS Score: 7.7 (High)
• Affected SNMP Versions: 1, 2c, and 3
• Exploitation: Requires authenticated access
• Impact: Device reload, resulting in DoS

For leadership 🧭

This advisory highlights a High-risk vulnerability in Cisco IOS XE Software that could lead to denial of service if exploited. The vulnerability requires authenticated access, which limits exposure but still poses a significant risk to device availability. Organizations are advised to patch affected systems within 7 days to mitigate potential disruptions. The operational impact is expected to be minimal, involving a brief maintenance window with no expected configuration drift.

Now: Identify affected devices and prepare for patching.
Next: Apply the recommended software updates.
Later: Review SNMP configurations and access controls to enhance security.

Prompt action is essential to safeguard network operations against this vulnerability.