CVE-2021-34703 Cisco IOS and IOS XE Software Link Layer Discovery Protocol Denial of Service Vulnerability
An attacker can cause a denial of service by crashing Cisco IOS devices through LLDP message parsing flaws.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-34703?
CVE-2021-34703 is a medium-severity denial of service vulnerability in Cisco Ios, published on 23 Sep 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A vulnerability in the Link Layer Discovery Protocol (LLDP) message parser of Cisco IOS Software and Cisco IOS XE Software could allow an attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to improper initialization of a buffer. An attacker could exploit this vulnerability via any of the following methods: An authenticated, remote attacker could access the LLDP neighbor table via either the CLI or SNMP while the device is in a specific state. An unauthenticated, adjacent attacker could corrupt the LLDP neighbor table by injecting specific LLDP frames into the network and then waiting for an administrator of the device or a network management system (NMS) managing the device to retrieve the LLDP neighbor table of the device via either the CLI or SNMP. An authenticated, adjacent attacker with SNMP read-only credentials or low privileges on the device CLI could corrupt the LLDP neighbor table by injecting specific LLDP frames into the network and then accessing the LLDP neighbor table via either the CLI or SNMP. A successful exploit could allow the attacker to cause the affected device to crash, resulting in a reload of the device.
Which versions are affected by CVE-2021-34703?
It affects 2 products.
Products include Cisco Ios, Cisco Ios Xe.
How do I fix CVE-2021-34703?
No fix has been published for CVE-2021-34703 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-34703 being exploited?
There is no known exploitation of CVE-2021-34703 in the wild and no public exploit code.
Other vulnerabilities in Cisco Ios
- CVE-2017-12240 Cisco IOS and IOS XE Software DHCP Remote Code Execution
- CVE-2017-3881 Cisco IOS and IOS XE Remote Code Execution
- CVE-2018-0167 Cisco IOS, XR, and XE Software Buffer Overflow
- CVE-2017-6736 Cisco IOS and IOS XE Software SNMP Remote Code Execution
- CVE-2017-6737 Cisco IOS and IOS XE Software SNMP Remote Code Execution
Sources
Also known as GHSA-h43v-fh8q-w87r.