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Glossary Glossary

SNMP Vulnerability




An SNMP vulnerability is a weakness in the handling of Simple Network Management Protocol (SNMP) requests that attackers can exploit to gain unauthorized access to network infrastructure devices, steal sensitive data, or launch denial-of-service (DoS) attacks.

SNMP is a widely used protocol for monitoring and managing network devices like routers, switches, and servers. It allows network administrators to collect information about a device’s status, performance, and configuration. However, it can also be a potential source of security risks, as attackers can abuse it by sending SNMP requests to vulnerable network devices.

Table of Contents

SNMP Vulnerability: A Deep Dive

What Are Examples of SNMP Vulnerabilities?

CVE-2017-6742

One of the most widely known SNMP security issues is CVE-2017-6742. This SNMP vulnerability was found in Cisco IOS and IOS XE software, allowing attackers to execute malicious code remotely or cause an affected system to reload.

This security vulnerability is quite severe, with a Common Vulnerability Scoring System (CVSS) rating of 8.8. However, Cisco has already released software updates to address this vulnerability.

CVE-2025-20352

More recently, in September 2025, another Cisco IOS vulnerability was found, affecting Cisco IOS Software and Cisco IOS XE Software. The vulnerability, with CVE ID CVE-2025-20352, could allow authenticated remote attackers, even those with low privileges, to target affected devices in a denial-of-service (DoS) attack. 

The vulnerability has already been exploited in a zero-day attack where threat actors deployed Linux rootkits to achieve remote code execution.

CVE-2025-20352 affects all versions of SNMP and has a CVSS rating of 7.7, indicating high severity. CISCO has released an advisory on October 6, 2025, saying that while there is no workaround, organizations can take specific measures to mitigate the vulnerability, which include:

  • Allowing only trusted users to have SNMP access on affected systems
  • Monitor affected systems through the show snmp host command
  • Disable the affected Object Identifiers (OIDs) on devices

More details about these and other mitigating measures can be found on Cisco’s advisory.

Other SNMP Vulnerabilities

In February 2025, a similar set of vulnerabilities was found in the same products (Cisco IOS Software and Cisco IOS XE Software), although Cisco has already released fixes. These vulnerabilities are:

How Do Attackers Exploit an SNMP Vulnerability?

An attacker can exploit SNMP weaknesses in various ways, such as targeting weak community strings, unencrypted SNMP versions, and incorrect access control settings. We’ll talk more about each of the issues below.

  • Weak or default community strings: Community strings are used to authenticate SNMP requests. Attackers can discover them by scanning networks for SNMP devices and sending widely used community strings to see if they work. If attackers manage to guess the community string for a network infrastructure device, they can send SNMP requests to control or steal data from it.
  • Outdated SNMP versions: Old versions of SNMP (i.e., SNMPv1 and SNMPv2c) do not support network traffic encryption, which means attackers can capture and analyze SNMP packets to gain insights into a network, including its configuration and security vulnerabilities. Attackers can use this information to launch further attacks, such as targeting specific devices or exploiting other vulnerabilities. Organizations are advised to upgrade to SNMPv3 since this version supports encryption.
  • Incorrect access control settings: SNMP agents and managers should be configured to restrict access to authorized users and devices only. However, some SNMP implementations may have incorrect access control permissions, which could allow unauthorized users to perform SNMP operations. Attackers can exploit incorrect access control permissions by sending SNMP requests from unauthorized devices or using unauthorized credentials.

How Can an SNMP Vulnerability Exploitation Impact an Organization?

Depending on the nature of the vulnerability and how it is exploited, an SNMP security issue may put organizations at risk of data theft, DoS attacks, and disruption to network operations.

SNMP vulnerabilities undoubtedly widen an organization’s attack surface, giving attackers potential entry points to affected systems and the entire network. The ultimate impact of this vulnerability could be financial loss, reputational damage, and even regulatory compliance violations.

How Do You Detect and Protect against SNMP Vulnerabilities?

Below are some ways to prevent vulnerabilities in the SNMP subsystem.

  • Upgrade to SNMPv3, the most secure SNMP version.
  • Change default community strings to strong and complex ones, especially if you’re still using older SNMP versions.
  • Use automated tools like ASM solutions and vulnerability scanners to scan your network for SNMP vulnerabilities. 
SNMP Vulnerability

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Vulnerabilities in the SNMP subsystem, like CVE-2017-6742 and CVE-2025-20352, expose an organization to costly threats that may disrupt business operations. Constantly monitoring your systems for these vulnerabilities can help minimize risks.

Key Takeaways

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