Cisco IOS/IOS XE SNMP Subsystem denial of service

Summaryinfo

A vulnerability was found in Cisco IOS and IOS XE. It has been declared as problematic. This vulnerability affects unknown code of the component SNMP Subsystem. Executing a manipulation can lead to denial of service. This vulnerability appears as CVE-2025-20173. The attack may be performed from remote. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco IOS and IOS XE (version now known). It has been declared as critical. This vulnerability affects some unknown processing of the component SNMP Subsystem. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. CVE summarizes:

A vulnerability in the SNMP subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to cause a DoS condition on an affected device. This vulnerability is due to improper error handling when parsing SNMP requests. An attacker could exploit this vulnerability by sending a crafted SNMP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition.  This vulnerability affects SNMP versions 1, 2c, and 3. To exploit this vulnerability through SNMP v2c or earlier, the attacker must know a valid read-write or read-only SNMP community string for the affected system. To exploit this vulnerability through SNMP v3, the attacker must have valid SNMP user credentials for the affected system.

The advisory is shared for download at sec.cloudapps.cisco.com. This vulnerability was named CVE-2025-20173 since 10/10/2024. The exploitation appears to be easy. The attack can be initiated remotely. Required for exploitation is a single authentication. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 215126 (Cisco IOS Software SNMP DoS (cisco-sa-snmp-dos-sdxnSUcW)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (215126). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Router Operating System

Vendor

• Cisco

Name

• IOS
• IOS XE

License

• commercial

Website

• Vendor: https://www.cisco.com/

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Once again VulDB remains the best source for vulnerability data.

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