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CVE-2021-34703 : Security Advisory and Response

Learn about CVE-2021-34703 impacting Cisco IOS and IOS XE Software. Find out how attackers can exploit the LLDP vulnerability, its impact, and mitigation steps.

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.

Understanding CVE-2021-34703

This CVE identifies a critical vulnerability in Cisco IOS and IOS XE Software that could lead to a denial of service condition.

What is CVE-2021-34703?

The vulnerability stems from improper initialization of a buffer in the LLDP message parser, allowing an attacker to crash the device by exploiting the LLDP neighbor table.

The Impact of CVE-2021-34703

This vulnerability could be exploited by authenticated or adjacent attackers to cause affected devices to reload, leading to service disruption.

Technical Details of CVE-2021-34703

This section delves into the specifics of the vulnerability.

Vulnerability Description

The vulnerability allows attackers to crash the device by corrupting the LLDP neighbor table, exploiting improper buffer initialization.

Affected Systems and Versions

Cisco IOS Software and Cisco IOS XE Software are affected by this vulnerability.

Exploitation Mechanism

Attackers, whether authenticated, adjacent, or remote, can trigger the reload of an affected device by manipulating the LLDP neighbor table.

Mitigation and Prevention

To safeguard your systems, take the following steps:

Immediate Steps to Take

        Apply official patches and updates from Cisco to address the vulnerability.
        Monitor network traffic for any signs of unauthorized LLDP frame injections.

Long-Term Security Practices

        Regularly update and patch your network devices to protect against known vulnerabilities.
        Employ network segmentation and access controls to limit unauthorized access.

Patching and Updates

Stay informed about security advisories from Cisco and promptly apply relevant patches to secure your systems.

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