Cisco SNMP Vulnerability (CVE-2025-20352): What You Need to Know — and How to Remediate with rConfig

On September 24, 2025, Cisco disclosed a serious vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE software, tracked as CVE-2025-20352.

This stack overflow flaw can be exploited by an authenticated attacker:

• With low privileges, they can cause a denial of service (DoS) by forcing the device to reload.

• With high privileges (SNMPv1/v2c read-only string or SNMPv3 admin credentials), they could achieve remote code execution as root, giving them full device control.

Cisco has confirmed that this vulnerability has been exploited in the wild. A patch is already available in IOS XE 17.15.4a, and no permanent workaround exists other than upgrading.

🔗 Cisco’s official advisory
🔗 Press coverage

Mitigation Options

If patching is not immediately possible, Cisco recommends:

• Limiting SNMP access to trusted users only.

• Monitoring with show snmp host.

• Excluding affected OIDs with an snmp-server view configuration.

Example Cisco mitigation snippet (from Cisco advisory):

! Standard VIEW and Security Exclusions
snmp-server view NO_BAD_SNMP iso included
snmp-server view NO_BAD_SNMP snmpUsmMIB excluded
snmp-server view NO_BAD_SNMP snmpVacmMIB excluded
snmp-server view NO_BAD_SNMP snmpCommunityMIB excluded

! Advisory Specific Mapping
snmp-server view NO_BAD_SNMP cafSessionMethodsInfoEntry.2.1.111 excluded 

! Apply mitigation
snmp-server community mycomm view NO_BAD_SNMP RO
snmp-server group v3group auth read NO_BAD_SNMP write NO_BAD_SNMP

How rConfig Helps

With rConfig’s Snippets feature, you can:

• Push this Cisco-recommended mitigation snippet across all affected IOS/IOS XE devices in minutes.

• Validate compliance at scale by verifying devices have the correct SNMP views applied.

• Roll back or adjust SNMP configs centrally when permanent upgrades are complete.

This vulnerability highlights the need for fast, repeatable config changes during zero-day and high-risk events. rConfig enables teams to implement vendor guidance quickly, ensuring consistent protection across large, distributed networks.

Next Steps

1. Check if your devices are running vulnerable versions of IOS/IOS XE and upgrade to 17.15.4a or later.

2. Apply Cisco’s recommended SNMP view exclusions using rConfig Snippets if patching will be delayed.

3. Use rConfig’s compliance reports to track which devices are remediated.

👉 Learn more about rConfig’s Snippets feature and how it accelerates security response.