Known exploited vulnerability · CISA KEV

CVE-2017-6742: Cisco IOS and IOS XE Software SNMP Remote Code Execution Vulnerability

The Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE contains a vulnerability that could allow an authenticated, remote attacker to remotely execute code on an affected system or cause an affected system to reload.

CVE-2017-6742

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2023-04-19: attackers are using it right now.

CISA KEV: Listed; Added 2023-04-19 · federal fix-by 2023-05-10
EPSS (30 days): 21%; Higher than 98% of CVEs · 2026-11-01
CVSS v3.1: 8.8 High; CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

What CISA says

Cisco IOS and IOS XE Software SNMP Remote Code Execution Vulnerability

Apply updates per vendor instructions.

NVD description · published 2017-07-17

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.

Full record on NVD

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How to check if you are exposed to CVE-2017-6742

Find every Cisco IOS and IOS XE Software system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2017-6742.

US federal agencies had to fix this by 2023-05-10. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2017-6742. Check the vendor advisory for the exact fixed builds before you sign anything off.

Product	Vulnerable versions
Cisco IOS	from 12.0 up to and including 12.4; from 15.0 up to and including 15.6
Cisco IOS XE	from 2.2.0 up to and including 3.17

Timeline

2017-07-17 · Published in the National Vulnerability Database
2023-04-19 · Added to CISA's Known Exploited Vulnerabilities catalog, 2,102 days after it was published
2023-05-10 · Fix-by date for US federal agencies, passed 1,271 days ago

Vendor advisories and fixes

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170629-snmp

Weakness type

CWE-119

More exploited Cisco vulnerabilities

CISA lists 102 exploited Cisco vulnerabilities. The closest matches:

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Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.