Cisco IOS and IOS XE SNMP Buffer Overflow (CVE-2025-20352)

Historical catalog analysis: CISA added this entry on September 29, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2025-20352 is a stack-based buffer overflow (CWE-121) located within the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE software. The vulnerability manifests differently based on the privilege level of the actor:

• Low-privileged actors: May trigger a system reload, resulting in a Denial of Service (DoS) condition.
• High-privileged actors: May execute arbitrary code with root privileges, potentially granting full control over the affected system.

Exposure and applicability

This vulnerability applies to infrastructure running Cisco IOS or IOS XE software where the SNMP subsystem is active. Exposure depends on whether the device is configured to accept SNMP traffic and the level of access an attacker has already obtained within the environment. Because high-privileged access is required for remote code execution (RCE), the risk profile shifts from availability (DoS) to complete system compromise as attacker permissions increase.

Remediation priorities

Our analysis suggests prioritizing remediation based on the criticality of the network asset and its current SNMP configuration. We recommend the following priority sequence:

1. Immediate Patching: Apply vendor-supplied mitigations for all devices where SNMP is enabled and exposed to untrusted or low-trust segments.
2. Privilege Review: Audit accounts with high-level privileges that have access to the SNMP subsystem, as these represent the highest risk for RCE.
3. Service Decommissioning: If a device does not require SNMP for operational monitoring and no mitigation is available, discontinue use of the product or disable the service entirely.

How to validate remediation

Verification must go beyond checking software version numbers. To ensure exposure is reduced, defenders should:

• Confirm Mitigation Application: Verify that vendor-specific patches or configuration changes have been successfully applied and persisted across reboots.
• Validate Access Controls: Confirm that SNMP access is restricted to authorized management stations via Access Control Lists (ACLs), reducing the surface area for both low- and high-privileged actors.
• Configuration Audit: Ensure that any legacy or default SNMP configurations have been replaced with secure, authenticated versions as specified in vendor guidance.

Limits and open questions

It remains unknown whether this vulnerability has been utilized in known ransomware campaigns. Additionally, the source does not specify the exact software versions affected; defenders must consult the Cisco Security Advisory to map their specific inventory to the vulnerable ranges. There is a residual risk that existing high-privileged credentials could be used to exploit the RCE path even after some perimeter controls are implemented, necessitating internal identity and access management (IAM) reviews.

Source and editorial note

CVE-2025-20352: Cisco IOS and IOS XE Software SNMP Denial of Service and Remote Code Execution Vulnerability · Source date: September 29, 2025 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: October 02, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: October 01, 2026 at 01:20 UTC.

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