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

Summary

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

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

Remediation

Known exploitation

99% probability of exploitation in the next 30 days (percentile 100%).

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CERT-FR

No CERT-FR advisory or alert of the last two years references this CVE, for the vendors Patcharo covers.

Timeline

1. 17 Mar 2017Published by the source
2. 25 Mar 2022Added to CISA KEV
3. 15 Apr 2022CISA remediation due date
4. 17 Jun 2026Source record last modified
5. 27 Sept 2026EPSS score computed
6. 1 Oct 2026Last verified by Patcharo

Official sources

• Cisco (CVE record)retrieved 1 Oct 2026 at 09:31 UTC
• CISA Known Exploited Vulnerabilitiesretrieved 1 Oct 2026 at 09:28 UTC
• NVDretrieved 27 Sept 2026 at 23:44 UTC
• FIRST EPSSretrieved 27 Sept 2026 at 23:46 UTC
• Cisco Security Advisory cisco-sa-20170317-cmpretrieved 1 Oct 2026 at 09:31 UTC

Cisco · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS · Cisco Security Advisory cisco-sa-20170317-cmp