Known exploited vulnerability · CISA KEV

CVE-2017-6743: 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.

CVE-2017-6743

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2022-03-03: attackers are using it right now.

CISA KEV: Listed; Added 2022-03-03 · federal fix-by 2022-03-24
EPSS (30 days): 11%; Higher than 96% 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

The Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE Software contains multiple vulnerabilities that could allow an authenticated, remote attacker to remotely execute code on an affected system or cause an affected system to reload. An attacker could exploit these vulnerabilities by sending a crafted SNMP packet to an affected system via IPv4 or IPv6. Only traffic directed to an affected system can be used to exploit these vulnerabilities. The vulnerabilities are due to a buffer overflow condition in the SNMP subsystem of the affected software. The vulnerabilities affect all versions of SNMP - Versions 1, 2c, and 3. To exploit these vulnerabilities via SNMP Version 2c or earlier, the attacker must know the SNMP read-only community string for the affected system. To exploit these vulnerabilities via SNMP Version 3, the attacker must have user credentials for the affected system. A successful exploit could allow the attacker to execute arbitrary code and obtain full control of the affected system or cause the affected system to reload. Customers are advised to apply the workaround as contained in the Workarounds section below. Fixed software informati

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How to check if you are exposed to CVE-2017-6743

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. 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-2017-6743.

US federal agencies had to fix this by 2022-03-24. 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-2017-6743. 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
2022-03-03 · Added to CISA's Known Exploited Vulnerabilities catalog, 1,690 days after it was published
2022-03-24 · Fix-by date for US federal agencies, passed 1,683 days ago

Weakness type

CWE-119

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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.