CVE-2017-6742 in IOS
Summary
by MITRE
A vulnerability in the SNMP implementation of could allow an authenticated, remote attacker to cause a reload of the affected system or to remotely execute code. An attacker could exploit this vulnerability by sending a crafted SNMP packet to the affected device.
The vulnerability is due to a buffer overflow in the affected code area. The vulnerability affects all versions of SNMP (versions 1, 2c, and 3). The attacker must know the SNMP read only community string (SNMP version 2c or earlier) or the user credentials (SNMPv3). An exploit could allow the attacker to execute arbitrary code and obtain full control of the system or to cause a reload of the affected system.
Only traffic directed to the affected system can be used to exploit this vulnerability.
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Analysis
by VulDB Data Team • 01/13/2026
The vulnerability identified as CVE-2017-6742 represents a critical buffer overflow flaw within the Simple Network Management Protocol (SNMP) implementation of affected network devices. This weakness exists in the handling of SNMP packets and affects all versions of SNMP including versions 1, 2c, and 3, making it particularly dangerous as it spans multiple protocol iterations. The vulnerability stems from insufficient input validation and memory management within the SNMP processing code, creating a condition where maliciously crafted packets can overflow allocated buffers and potentially overwrite critical memory segments. The flaw specifically manifests when the system processes incoming SNMP packets without adequate bounds checking, allowing attackers to manipulate memory layout through carefully constructed payloads that exceed buffer capacity.
The operational impact of this vulnerability extends beyond simple system disruption to encompass complete system compromise and unauthorized code execution. An authenticated remote attacker who possesses valid SNMP credentials can leverage this flaw to achieve arbitrary code execution on the target system, effectively granting them full administrative control. The attack vector requires only that malicious packets be sent to the vulnerable device, making it particularly concerning as it can be exploited from external network positions without requiring physical access. This vulnerability directly maps to CWE-121, which describes buffer overflow conditions in heap-based memory allocation, and also aligns with CWE-787, representing out-of-bounds write vulnerabilities. The potential for system reload or complete takeover makes this a high-severity issue that could enable persistent access to network infrastructure.
The exploitability of CVE-2017-6742 is constrained by the requirement for authentication, as attackers must possess valid SNMP community strings for versions 1 and 2c or valid user credentials for SNMPv3 to successfully execute the attack. This authentication requirement provides some defense-in-depth but does not eliminate the threat, as SNMP community strings are often weak or default configurations that can be easily discovered through network scanning or credential brute-forcing attacks. The vulnerability's impact on network infrastructure is significant because SNMP is widely deployed across enterprise networks for device monitoring and management, making the attack surface extensive. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and T1059 which covers command and scripting interpreter, as successful exploitation would allow attackers to execute arbitrary commands and maintain persistence. The attack chain typically involves reconnaissance to identify vulnerable devices, credential gathering or guessing, and then payload delivery through crafted SNMP packets that trigger the buffer overflow condition.
Mitigation strategies for CVE-2017-6742 should prioritize immediate patching of affected systems, as vendors released security updates to address the buffer overflow condition. Network segmentation and access control measures should be implemented to limit SNMP access to trusted networks and administrative systems only. Configuration hardening practices including disabling unnecessary SNMP versions, implementing strong community strings, and enforcing SNMPv3 with robust authentication mechanisms are essential. Network monitoring should include detection of anomalous SNMP traffic patterns and signature-based detection of known exploit payloads. Regular vulnerability assessments and penetration testing should be conducted to identify unpatched systems and ensure proper SNMP configuration. Additionally, implementing network access control lists and firewalls to restrict SNMP traffic to authorized management stations helps minimize exposure. The vulnerability serves as a reminder of the importance of input validation and secure coding practices, particularly in network protocol implementations where external input processing is critical to system operation and security.