CVE-2017-3881 Cisco IOS and IOS XE Remote Code Execution

Exploited in the wild Critical 9.8 Published 17 Mar 2017 Updated 12 Jan 2026

Unauthenticated remote attackers can execute arbitrary code or cause device reloads via malformed Telnet options in Cisco IOS and IOS XE.

Exploited in the wild: Since 25 Mar 2022
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2017-3881?

CVE-2017-3881 is a critical code injection vulnerability in Cisco Ios, published on 17 Mar 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A vulnerability in the Cisco Cluster Management Protocol (CMP) processing code in Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a reload of an affected device or remotely execute code with elevated privileges. The Cluster Management Protocol utilizes Telnet internally as a signaling and command protocol between cluster members. The vulnerability is due to the combination of two factors: (1) the failure to restrict the use of CMP-specific Telnet options only to internal, local communications between cluster members and instead accept and process such options over any Telnet connection to an affected device; and (2) the incorrect processing of malformed CMP-specific Telnet options. An attacker could exploit this vulnerability by sending malformed CMP-specific Telnet options while establishing a Telnet session with an affected Cisco device configured to accept Telnet connections. An exploit could allow an attacker to execute arbitrary code and obtain full control of the device or cause a reload of the affected device. This affects Catalyst switches, Embedded Service 2020 switches, Enhanced Layer 2 EtherSwitch Service Module, Enhanced Layer 2/3 EtherSwitch Service Module, Gigabit Ethernet Switch Module (CGESM) for HP, IE Industrial Ethernet switches, ME 4924-10GE switch, RF Gateway 10, and SM-X Layer 2/3 EtherSwitch Service Module. Cisco Bug IDs: CSCvd48893.

Weakness: CWE-20

Which versions are affected by CVE-2017-3881?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2017-3881?

No fix has been published for CVE-2017-3881 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 15 Apr 2022.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2017-3881 being exploited?

Yes. Attackers have exploited CVE-2017-3881 in the wild since at least 25 Mar 2022.

Public exploit code: 1 Metasploit module, 2 Exploit-DB entries, 1 Nuclei template and 5 proofs of concept on GitHub.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-g37w-qg7v-7fjq.