CVE-2017-6740 Cisco IOS and IOS XE Software SNMP Remote Code Execution

Exploited in the wild High 8.8 Published 17 Jul 2017 Updated 21 Oct 2025

Authenticated remote attackers can execute arbitrary code or cause reloads on Cisco IOS devices via crafted SNMP packets due to buffer overflows.

Exploited in the wild: Since 3 Mar 2022
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2017-6740?

CVE-2017-6740 is a high-severity memory corruption vulnerability in Cisco Ios, published on 17 Jul 2017. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

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 information is available via the Cisco IOS Software Checker. All devices that have enabled SNMP and have not explicitly excluded the affected MIBs or OIDs should be considered vulnerable. There are workarounds that address these vulnerabilities.

Weakness: CWE-119

Which versions are affected by CVE-2017-6740?

It affects 2 products.

Products include Cisco Ios, Cisco Ios Xe.

How do I fix CVE-2017-6740?

No fix has been published for CVE-2017-6740 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 24 Mar 2022.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2017-6740 being exploited?

Yes. Attackers have exploited CVE-2017-6740 in the wild since at least 3 Mar 2022.

All Cisco Ios vulnerabilities

Sources

Also known as GHSA-vmp6-vfp8-8398.