CVE-2025-20312 in IOS XE
Summary
by MITRE • 09/24/2025
A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
This vulnerability is due to improper error handling when parsing a specific SNMP request. An attacker could exploit this vulnerability by sending a specific 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 SNMPv2c 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 SNMPv3, the attacker must have valid SNMP user credentials for the affected system.
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Analysis
by VulDB Data Team • 10/28/2025
The vulnerability identified as CVE-2025-20312 represents a critical denial of service weakness within Cisco IOS XE Software's Simple Network Management Protocol implementation. This flaw resides in the SNMP subsystem's error handling mechanisms, specifically when processing certain malformed or crafted SNMP requests. The vulnerability demonstrates how insufficient input validation and error management can create exploitable conditions that compromise system availability. From a cybersecurity perspective, this issue exemplifies the importance of robust error handling in network infrastructure software where malicious actors can leverage seemingly minor implementation flaws to cause significant operational disruptions. The vulnerability affects multiple SNMP versions including v1, v2c, and v3, indicating a widespread impact across different SNMP protocol iterations that organizations typically deploy in their network management infrastructures.
The technical exploitation of CVE-2025-20312 requires an authenticated attacker who can successfully establish communication with the target device using valid SNMP credentials. For SNMP versions 1 and 2c, attackers must possess valid community strings with read-write or read-only privileges to execute the attack successfully. In the case of SNMPv3, attackers need valid user credentials including appropriate authentication and privacy parameters. This authentication requirement limits the attack surface but does not eliminate the threat, as compromised credentials or weak credential management practices can still enable exploitation. The vulnerability manifests through improper error handling during SNMP request parsing, where the system fails to properly validate or sanitize incoming request parameters. This inadequate validation allows specially crafted requests to trigger unexpected behavior in the SNMP subsystem, ultimately leading to device reload operations that result in denial of service conditions. The error handling flaw creates a path where malformed input can cause the device to enter an unstable state, forcing system restarts that disrupt network operations.
The operational impact of this vulnerability extends beyond simple service interruption to potentially disrupt critical network management functions that depend on SNMP for monitoring and configuration. Network administrators rely on SNMP for device status monitoring, performance tracking, and configuration management, making any DoS condition that affects SNMP subsystem particularly concerning. Organizations with extensive SNMP deployments across their network infrastructure face significant risk from this vulnerability, as multiple devices could be simultaneously affected. The vulnerability's exploitation can lead to cascading failures where network monitoring systems become unavailable, making it difficult for administrators to detect and respond to other potential security incidents. Additionally, the automatic device reloading process can result in loss of configuration changes, disruption of network services, and potential data loss during the restart process. From a compliance standpoint, this vulnerability could impact organizations' ability to maintain continuous network availability, potentially violating service level agreements and regulatory requirements for network uptime.
Mitigation strategies for CVE-2025-20312 should focus on immediate patch deployment as the primary defense mechanism, alongside network segmentation and access control measures. Organizations should prioritize updating their Cisco IOS XE devices to versions that contain the vulnerability fix, while implementing strict SNMP access controls to limit the number of devices with valid community strings or user credentials. Network segmentation can help contain the impact by isolating SNMP-accessible devices from critical network segments. Implementing SNMPv3 with strong authentication and encryption mechanisms provides additional protection, though administrators must ensure proper credential management to prevent unauthorized access. Monitoring systems should be enhanced to detect unusual SNMP traffic patterns or repeated connection attempts that might indicate exploitation attempts. Network administrators should also implement automated alerting for device reload events, as these can serve as indicators of successful exploitation. The vulnerability aligns with CWE-248, which addresses "Uncaught Exception," and maps to ATT&CK technique T1499.004 for "Endpoint Denial of Service," highlighting the need for comprehensive defensive measures that address both the immediate vulnerability and broader network security posture. Regular security assessments and vulnerability scanning should include verification of SNMP configuration settings to ensure that only necessary devices have SNMP access and that credentials are properly managed and rotated.