CVE-2025-20207: Cisco Email Security SNMP Vulnerability

CVE-2025-20207 Overview

CVE-2025-20207 is an information disclosure vulnerability affecting Cisco Secure Email and Web Manager, Cisco Secure Email Gateway, and Cisco Secure Web Appliance. The flaw exists in the Simple Network Management Protocol (SNMP) polling implementation. An authenticated remote attacker with valid SNMP credentials can send crafted SNMP poll requests to retrieve confidential information about the underlying operating system. The weakness is categorized under [CWE-200], exposure of sensitive information to an unauthorized actor.

Critical Impact
Authenticated attackers with configured SNMP credentials can harvest operating system details that should remain restricted, enabling targeted follow-on attacks against the Cisco appliance.

Affected Products

Cisco Secure Email and Web Manager
Cisco Secure Email Gateway
Cisco Secure Web Appliance

Discovery Timeline

2025-02-05 - CVE-2025-20207 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20207

Vulnerability Analysis

The vulnerability stems from the way affected Cisco appliances handle SNMP poll requests. The appliances fail to protect confidential information at rest when responding to SNMP queries. An authenticated attacker who possesses the configured SNMP community string or SNMPv3 credentials can issue crafted polls that return operating system data intended to be restricted.

The exploitation path requires network access to the SNMP service and valid SNMP credentials. No user interaction is required. The scope of impact is limited to confidentiality; integrity and availability of the appliance are not affected. The disclosed data can support reconnaissance for later exploitation of the host operating system or appliance management plane.

Root Cause

The root cause is missing access control over sensitive data returned via SNMP OIDs. The management information base entries exposed by the appliance include operating system details that should be gated behind stricter authorization or redacted before transmission.

Attack Vector

An attacker authenticates to the SNMP service using the configured credentials and sends a crafted SNMP GET or GETNEXT poll request. The appliance returns operating system information in its response payload. No verified public proof of concept is available. See the Cisco Security Advisory for vendor-specific technical details.

Detection Methods for CVE-2025-20207

Indicators of Compromise

Unexpected SNMP poll requests from unfamiliar source IP addresses targeting Cisco Secure Email, Web Manager, or Web Appliance management interfaces.
Abnormally high volume or breadth of SNMP OID walks against affected appliances, suggesting enumeration activity.
SNMP authentication events using service accounts outside normal monitoring windows or source networks.

Detection Strategies

Baseline legitimate SNMP pollers and alert on queries originating from any other source toward the affected appliances.
Inspect SNMP response payloads at the network boundary for OID branches that reveal operating system metadata.
Correlate SNMP activity with authentication logs on the appliance to identify use of SNMP credentials from unexpected hosts.

Monitoring Recommendations

Forward Cisco appliance logs and NetFlow data covering UDP port 161 into a centralized analytics platform for retention and search.
Enable alerting on repeated SNMP GETNEXT or GETBULK walks that traverse large portions of the MIB tree.
Review SNMP community string and SNMPv3 user usage on a recurring basis to detect credential reuse or compromise.

How to Mitigate CVE-2025-20207

Immediate Actions Required

Apply the fixed software releases listed in the Cisco Security Advisory for Secure Email and Web Manager, Secure Email Gateway, and Secure Web Appliance.
Rotate all configured SNMP community strings and SNMPv3 credentials on affected appliances.
Restrict SNMP access with access control lists so that only authorized management hosts can reach UDP port 161 on the appliances.

Patch Information

Cisco has published fixed software versions through its security advisory. Administrators should consult the vendor advisory for the specific train and release matrix that addresses CVE-2025-20207 for each affected product. No workaround fully substitutes for the patch.

Workarounds

Disable SNMP polling on affected appliances if the service is not required for operational monitoring.
Enforce SNMPv3 with authentication and privacy, and remove any legacy SNMPv1 or SNMPv2c community strings where feasible.
Place the appliance management interface on an isolated out-of-band network reachable only by authorized monitoring systems.

bash

# Configuration example
# Restrict SNMP access to authorized monitoring hosts only
# Replace with the actual trusted management network and credentials
snmpconfig
# When prompted, limit allowed hosts to a specific subnet and
# require SNMPv3 with authPriv (authentication and encryption)