CVE-2025-20170 in IOS
Summary
by MITRE • 02/05/2025
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.
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Analysis
by VulDB Data Team • 07/03/2025
This vulnerability resides within the Simple Network Management Protocol subsystem of Cisco's networking operating systems, specifically affecting both IOS and IOS XE software implementations. The flaw manifests as inadequate error handling mechanisms during the processing of SNMP requests, creating a condition where malformed or specially crafted packets can trigger unexpected system behavior. The vulnerability impacts all three major SNMP versions, indicating a fundamental flaw in the protocol parsing logic that extends across multiple generations of the implementation. This represents a significant concern for network infrastructure devices that rely heavily on SNMP for monitoring and management operations, as the affected systems could become unavailable due to unexpected restarts.
The technical exploitation of this vulnerability requires an authenticated attacker who can send specifically crafted SNMP requests to the target device. The improper error handling causes the system to enter an unstable state when processing these malformed requests, ultimately leading to an unexpected device reload. This behavior constitutes a denial of service condition that can disrupt network monitoring, management, and operational functions. The attack vectors differ slightly between SNMP versions, with v2c and earlier requiring knowledge of valid community strings for read-write or read-only access, while SNMP v3 requires valid user credentials for authentication. This authentication requirement does not eliminate the threat but rather indicates the vulnerability exists at the protocol parsing layer regardless of the security mechanism used.
The operational impact of this vulnerability extends beyond simple service disruption, as network administrators may face unexpected device reboots that could occur without warning or clear indication of the underlying cause. This can complicate troubleshooting efforts and potentially mask other security incidents that might be occurring simultaneously. The vulnerability affects critical network infrastructure components that typically operate continuously, making unexpected reloads particularly disruptive to network availability and reliability. Organizations relying on SNMP-based monitoring systems may experience gaps in their monitoring capabilities during device restarts, potentially leading to undetected security incidents or performance degradation.
Network security teams should prioritize patching affected devices as soon as vendor advisories become available, as this vulnerability can be exploited remotely by authenticated attackers. The remediation approach should involve applying the latest software updates from Cisco that address the SNMP parsing error handling issues. Network segmentation and access control measures should be reviewed to ensure that only authorized personnel have the ability to send SNMP requests to critical infrastructure devices. Monitoring should be enhanced to detect unusual device restart patterns or SNMP traffic anomalies that might indicate exploitation attempts. This vulnerability aligns with CWE-248, which addresses "Uncaught Exception," and represents a potential ATT&CK technique under T1499.004 for "Endpoint Denial of Service" through network service disruption. Organizations should also consider implementing SNMP access controls and limiting SNMP community string usage to reduce the attack surface for this particular vulnerability.