CVE-2017-6738 is a SNMP remote code execution vulnerability in Cisco IOS and IOS XE Software. CISA added it to the Known Exploited Vulnerabilities catalogue on 3 March 2022, which means attackers have used it in real attacks. Organisations running the affected product should apply the vendor fix or mitigation as a priority.
What SNMP exploitation means in Cisco IOS and IOS XE
snmp remote code execution means an attacker can abuse the device management interface to execute code on the network device itself. On routers and switches, that matters because the control plane is highly privileged and often trusted to keep traffic flowing, route correctly and enforce security policy.
This is not a generic application flaw, it is a vulnerability in exposed network infrastructure. When SNMP is reachable and the device is vulnerable, the impact can extend beyond one box into routing stability, monitoring integrity and the confidentiality of configuration data.
Why this vulnerability is dangerous
SNMP is commonly used for inventory, telemetry and administration, which makes it especially valuable to attackers once they obtain a path to it. A remote code execution flaw in that service can turn routine management exposure into direct device compromise, which is why command-and-control infrastructure often starts by targeting exposed enterprise systems and then using them as footholds.
In network gear, successful exploitation can enable configuration tampering, credential theft from the device, traffic interception or persistence on critical infrastructure. Because these systems often sit at the centre of segmentation and remote access design, compromise can create disproportionate downstream exposure.
How organisations assess exposure and reduce attack surface
Exposure checks should start with an inventory of Cisco IOS and IOS XE assets, a review of where SNMP is enabled, and confirmation of whether those interfaces are reachable from untrusted networks. Vendor advisories and the NIST National Vulnerability Database and CVE Program are the right places to confirm authoritative identification and tracking details.
Where patching is delayed, organisations should narrow exposure by restricting SNMP access to trusted management networks, limiting management-plane reachability and disabling unused services. For vulnerability prioritisation and verification workflows, the Vulnerability Management Guide is a useful model for turning KEV-listed issues into remediation priority.
Detection and recovery after suspected exploitation
Detection should look for unexpected device changes, unexplained reloads, unusual management traffic and signs that router or switch configuration has been modified. If exploitation is suspected, treat the device as potentially compromised rather than assuming that a single configuration rollback is enough.
Recovery should include review of configuration integrity, firmware state and any credentials or secrets stored or used by the device. If the device was used for management or trust relationships, rotate any related administrative credentials, API keys, certificates or shared secrets that may have been exposed during compromise.
Risk and Threat Considerations
Remote code execution in core network infrastructure can give an intruder a stable foothold with broad visibility and control. The main risk is not only initial compromise, but the ability to tamper with routing, monitoring and administrative trust paths while remaining hard to notice.
Failure mechanism: A reachable SNMP service is abused to execute attacker-controlled code on the device, after which the attacker can alter configuration, harvest secrets or establish persistence.
Impact: Organisations can face network disruption, data exposure, loss of management integrity and follow-on compromise across connected systems that trust the device.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK addresses the attack and risk surface, while NIST SP 800-53 Rev 5 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | Directs timely remediation of exploitable software flaws like this CVE. |
| AC-4 — Information Flow Enforcement | Limits management-plane reachability to trusted administration paths. | |
| IA-5 — Authenticator Management | Supports rotation of credentials and secrets after suspected device compromise. | |
| Recommendation — Prioritise remediation of the Cisco IOS and IOS XE flaw under SI-2 and verify closure after patching. Restrict SNMP access paths with AC-4 so only approved management networks can reach the device. Rotate affected credentials and secrets under IA-5 if the device was potentially used to access them. | ||
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | Maps to tracking and remediating KEV-listed exploitable vulnerabilities. |
| CIS-12 — Network Infrastructure Management | Covers secure administration and hardening of routers and switches. | |
| Recommendation — Use CIS-7 to inventory the device, validate exposure and drive expedited remediation. Use CIS-12 to harden network infrastructure and remove unnecessary management exposure. | ||
| MITRE ATT&CK | T1021 — Remote Services | Remote management interfaces are common entry points for exploitation and follow-on access. |
| T1068 — Exploitation for Privilege Escalation | Remote code execution is a direct exploitation path that can yield elevated control on the device. | |
| Recommendation — Map exposed management services to ATT&CK T1021 and hunt for abnormal remote administration activity. Treat exploitation evidence as T1068 and investigate for post-exploitation privilege escalation on the device. | ||
Practitioner Guidance
Why practitioners should care: KEV-listed network-device flaws deserve immediate prioritisation because the same device often serves as both infrastructure and control point. If it is compromised, the attacker may inherit a trusted position inside the network.
Common misunderstanding: Teams sometimes treat SNMP as monitoring-only and underestimate its privilege. In practice, management-plane exposure must be governed like any other high-value administrative interface, with access tightly scoped and continuously reviewed.
Practitioner takeaway: Confirm whether the device is exposed, verify vendor remediation guidance, and treat any suspected compromise as a full integrity event, not just a patching task.
Related resources from NHI Mgmt Group
- CVE-2017-6742 (Cisco IOS and IOS XE Software SNMP Remote Code Execution)
- CVE-2017-6743 (Cisco IOS and IOS XE Software SNMP Remote Code Execution)
- CVE-2025-20352 (Cisco IOS and IOS XE Software SNMP Denial of Service and Remote Code Execution)
- CVE-2017-6744 (Cisco IOS Software SNMP Remote Code Execution)
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Reviewed and updated by the NHIMG editorial team on October 17, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org