CVE-2025-20352 in IOS
Summary
by MITRE • 09/24/2025
A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS Software and Cisco IOS XE Software could allow the following: An authenticated, remote attacker with low privileges could cause a denial of service (DoS) condition on an affected device that is running Cisco IOS Software or Cisco IOS XE Software. To cause the DoS, the attacker must have the SNMPv2c or earlier read-only community string or valid SNMPv3 user credentials. An authenticated, remote attacker with high privileges could execute code as the root user on an affected device that is running Cisco IOS XE Software. To execute code as the root user, the attacker must have the SNMPv1 or v2c read-only community string or valid SNMPv3 user credentials and administrative or privilege 15 credentials on the affected device. An attacker could exploit this vulnerability by sending a crafted SNMP packet to an affected device over IPv4 or IPv6 networks. This vulnerability is due to a stack overflow condition in the SNMP subsystem of the affected software. A successful exploit could allow a low-privileged attacker to cause the affected system to reload, resulting in a DoS condition, or allow a high-privileged attacker to execute arbitrary code as the root user and obtain full control of the affected system. Note: This vulnerability affects all versions of SNMP.
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Analysis
by VulDB Data Team • 10/29/2025
This vulnerability represents a critical stack overflow condition within the Simple Network Management Protocol subsystem of Cisco IOS and IOS XE software, classified under CWE-121 as a stack-based buffer overflow. The flaw manifests when the SNMP processing module fails to properly validate input data from crafted SNMP packets, leading to memory corruption that can be exploited by remote attackers. The vulnerability affects all versions of SNMP protocols including v1, v2c, and v3, making it particularly concerning given the widespread deployment of these protocols in enterprise network management. The attack vector requires network access over IPv4 or IPv6 protocols, enabling remote exploitation without physical access to the target device.
The technical implementation of this vulnerability allows for two distinct attack scenarios based on the attacker's privilege level and credentials. Low-privileged attackers with read-only community strings or valid SNMPv3 credentials can trigger a denial of service condition by causing system reloads, effectively disrupting network operations and availability. This aligns with ATT&CK technique T1499.004 for network denial of service attacks. High-privileged attackers with additional administrative credentials can escalate to root privileges and execute arbitrary code, providing complete system compromise. This privilege escalation scenario corresponds to ATT&CK technique T1068 for local privilege escalation and T1548.001 for abuse of privileges. The stack overflow occurs during SNMP packet processing, where insufficient input validation allows malicious data to overwrite stack memory regions, potentially leading to code execution or system instability.
The operational impact of this vulnerability extends beyond immediate service disruption to encompass complete system compromise and potential network-wide consequences. Organizations relying on SNMP for network monitoring and management face significant risk as attackers can leverage this vulnerability to gain unauthorized access to critical infrastructure. The DoS capability creates availability issues that can affect network operations and business continuity, while the code execution vulnerability provides attackers with persistent access to target systems. This vulnerability directly impacts the CIA triad by compromising confidentiality, integrity, and availability of network services. The exploitability requirements are relatively low since it only requires valid SNMP credentials, which are commonly configured in network environments for management purposes, making the attack surface particularly broad.
Mitigation strategies should focus on multiple defensive layers to address both the immediate vulnerability and broader security posture. Network segmentation and access control should be implemented to limit SNMP access to authorized management stations only, reducing the attack surface. Regular software updates and patches should be applied immediately upon availability, as Cisco has likely released fixes for this vulnerability. SNMP community strings should be changed from default values and strengthened with complex passwords, while SNMPv3 should be preferred over older versions due to its enhanced security features. Network monitoring should be enhanced to detect anomalous SNMP traffic patterns that may indicate exploitation attempts. Additional security controls including intrusion detection systems, firewall rules limiting SNMP access, and regular vulnerability assessments should be implemented to detect and prevent exploitation attempts. The vulnerability demonstrates the importance of proper input validation in network protocol implementations and the critical need for security updates in network infrastructure software.